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TCSH(1)                                                                TCSH(1)



NAME
       tcsh - C shell with file name completion and command line editing

SYNOPSIS
       tcsh [-bcdefFimnqstvVxX] [-Dname[=value]] [arg ...]
       tcsh -l

DESCRIPTION
       tcsh  is  an  enhanced but completely compatible version of the Berkeley UNIX C shell, csh(1).  It is a command
       language interpreter usable both as an interactive login shell  and  a  shell  script  command  processor.   It
       includes  a command-line editor (see The command-line editor), programmable word completion (see Completion and
       listing), spelling correction (see Spelling correction), a history mechanism (see  History  substitution),  job
       control  (see  Jobs)  and  a C-like syntax.  The NEW FEATURES section describes major enhancements of tcsh over
       csh(1).  Throughout this manual, features of tcsh not found in most csh(1) implementations  (specifically,  the
       4.4BSD  csh)  are  labeled  with '(+)', and features which are present in csh(1) but not usually documented are
       labeled with '(u)'.

   Argument list processing
       If the first argument (argument 0) to the shell is '-' then it is a login shell.  A login  shell  can  be  also
       specified by invoking the shell with the -l flag as the only argument.

       The rest of the flag arguments are interpreted as follows:

       -b  Forces  a ''break'' from option processing, causing any further shell arguments to be treated as non-option
           arguments.  The remaining arguments will not be interpreted as shell options.  This may  be  used  to  pass
           options  to  a shell script without confusion or possible subterfuge.  The shell will not run a set-user ID
           script without this option.

       -c  Commands are read from the following argument (which must be present,  and  must  be  a  single  argument),
           stored  in  the  command shell variable for reference, and executed.  Any remaining arguments are placed in
           the argv shell variable.

       -d  The shell loads the directory stack from ~/.cshdirs as described under Startup and shutdown, whether or not
           it is a login shell. (+)

       -Dname[=value]
           Sets the environment variable name to value. (Domain/OS only) (+)

       -e  The shell exits if any invoked command terminates abnormally or yields a non-zero exit status.

       -f  The  shell  does  not  load  any resource or startup files, or perform any command hashing, and thus starts
           faster.

       -F  The shell uses fork(2) instead of vfork(2) to spawn processes. (+)

       -i  The shell is interactive and prompts for its top-level input, even if it appears  to  not  be  a  terminal.
           Shells are interactive without this option if their inputs and outputs are terminals.

       -l  The shell is a login shell.  Applicable only if -l is the only flag specified.

       -m  The  shell  loads  ~/.tcshrc even if it does not belong to the effective user.  Newer versions of su(1) can
           pass -m to the shell. (+)

       -n  The shell parses commands but does not execute them.  This aids in debugging shell scripts.

       -q  The shell accepts SIGQUIT (see Signal handling) and behaves when it is used under a debugger.  Job  control
           is disabled. (u)

       -s  Command input is taken from the standard input.

       -t  The shell reads and executes a single line of input.  A '\' may be used to escape the newline at the end of
           this line and continue onto another line.

       -v  Sets the verbose shell variable, so that command input is echoed after history substitution.

       -x  Sets the echo shell variable, so that commands are echoed immediately before execution.

       -V  Sets the verbose shell variable even before executing ~/.tcshrc.

       -X  Is to -x as -V is to -v.

       --help
           Print a help message on the standard output and exit. (+)

       --version
           Print the version/platform/compilation options on the standard output and exit.  This information  is  also
           contained in the version shell variable. (+)

       After  processing  of flag arguments, if arguments remain but none of the -c, -i, -s, or -t options were given,
       the first argument is taken as the name of a file of commands, or ''script'', to be executed.  The shell  opens
       this file and saves its name for possible resubstitution by '$0'.  Because many systems use either the standard
       version 6 or version 7 shells whose shell scripts are not compatible with this shell, the  shell  uses  such  a
       'standard'  shell to execute a script whose first character is not a '#', i.e., that does not start with a com-
       ment.

       Remaining arguments are placed in the argv shell variable.

   Startup and shutdown
       A login shell begins by executing commands from the system files /etc/csh.cshrc and  /etc/csh.login.   It  then
       executes  commands  from files in the user's home directory: first ~/.tcshrc (+) or, if ~/.tcshrc is not found,
       ~/.cshrc, then ~/.history (or the value of the histfile shell variable), then ~/.login, and finally  ~/.cshdirs
       (or  the  value of the dirsfile shell variable) (+).  The shell may read /etc/csh.login before instead of after
       /etc/csh.cshrc, and ~/.login before instead of after ~/.tcshrc or ~/.cshrc and ~/.history, if so compiled;  see
       the version shell variable. (+)

       Non-login shells read only /etc/csh.cshrc and ~/.tcshrc or ~/.cshrc on startup.

       For examples of startup files, please consult http://tcshrc.sourceforge.net.

       Commands  like  stty(1)  and tset(1), which need be run only once per login, usually go in one's ~/.login file.
       Users who need to use the same set of files with both csh(1) and tcsh can have only a ~/.cshrc which checks for
       the  existence  of  the  tcsh  shell  variable  (q.v.)  before using tcsh-specific commands, or can have both a
       ~/.cshrc and a ~/.tcshrc which sources (see the builtin command)  ~/.cshrc.   The  rest  of  this  manual  uses
       '~/.tcshrc' to mean '~/.tcshrc or, if ~/.tcshrc is not found, ~/.cshrc'.

       In  the  normal case, the shell begins reading commands from the terminal, prompting with '> '.  (Processing of
       arguments and the use of the shell to process files containing command scripts are described later.)  The shell
       repeatedly  reads  a line of command input, breaks it into words, places it on the command history list, parses
       it and executes each command in the line.

       One can log out by typing '^D' on an empty line, 'logout' or 'login' or via the  shell's  autologout  mechanism
       (see  the autologout shell variable).  When a login shell terminates it sets the logout shell variable to 'nor-
       mal' or 'automatic' as appropriate, then executes commands from the files /etc/csh.logout and  ~/.logout.   The
       shell may drop DTR on logout if so compiled; see the version shell variable.

       The  names  of  the  system  login and logout files vary from system to system for compatibility with different
       csh(1) variants; see FILES.

   Editing
       We first describe The command-line editor.   The  Completion  and  listing  and  Spelling  correction  sections
       describe  two  sets of functionality that are implemented as editor commands but which deserve their own treat-
       ment.  Finally, Editor commands lists and describes the editor commands specific to the shell and their default
       bindings.

   The command-line editor (+)
       Command-line input can be edited using key sequences much like those used in GNU Emacs or vi(1).  The editor is
       active only when the edit shell variable is set, which it is by default in  interactive  shells.   The  bindkey
       builtin  can  display  and change key bindings.  Emacs-style key bindings are used by default (unless the shell
       was compiled otherwise; see the version shell variable), but bindkey can change the key  bindings  to  vi-style
       bindings en masse.

       The shell always binds the arrow keys (as defined in the TERMCAP environment variable) to

           down    down-history
           up      up-history
           left    backward-char
           right   forward-char

       unless  doing  so  would alter another single-character binding.  One can set the arrow key escape sequences to
       the empty string with settc to prevent these bindings.  The ANSI/VT100 sequences  for  arrow  keys  are  always
       bound.

       Other  key bindings are, for the most part, what Emacs and vi(1) users would expect and can easily be displayed
       by bindkey, so there is no need to list them here.  Likewise, bindkey can list the editor commands with a short
       description of each.

       Note  that  editor  commands  do not have the same notion of a ''word'' as does the shell.  The editor delimits
       words with any non-alphanumeric characters not in the shell variable wordchars, while the shell recognizes only
       whitespace and some of the characters with special meanings to it, listed under Lexical structure.

   Completion and listing (+)
       The  shell  is often able to complete words when given a unique abbreviation.  Type part of a word (for example
       'ls /usr/lost') and hit the tab key to run the complete-word editor command.  The shell completes the  filename
       '/usr/lost'  to  '/usr/lost+found/',  replacing the incomplete word with the complete word in the input buffer.
       (Note the terminal '/'; completion adds a '/' to the end of completed directories and a space  to  the  end  of
       other  completed words, to speed typing and provide a visual indicator of successful completion.  The addsuffix
       shell variable can be unset to prevent this.)  If no match is found (perhaps '/usr/lost+found' doesn't  exist),
       the  terminal  bell  rings.  If the word is already complete (perhaps there is a '/usr/lost' on your system, or
       perhaps you were thinking too far ahead and typed the whole thing) a '/' or space is added to  the  end  if  it
       isn't already there.

       Completion  works  anywhere in the line, not at just the end; completed text pushes the rest of the line to the
       right.  Completion in the middle of a word often results in leftover characters to the right of the cursor that
       need to be deleted.

       Commands  and  variables  can  be completed in much the same way.  For example, typing 'em[tab]' would complete
       'em' to 'emacs' if emacs were the only command on your system beginning with 'em'.  Completion can find a  com-
       mand  in  any  directory  in  path or if given a full pathname.  Typing 'echo $ar[tab]' would complete '$ar' to
       '$argv' if no other variable began with 'ar'.

       The shell parses the input buffer to determine whether the word you want to complete should be completed  as  a
       filename,  command or variable.  The first word in the buffer and the first word following ';', '|', '|&', '&&'
       or '||' is considered to be a command.  A word beginning with '$' is considered to  be  a  variable.   Anything
       else is a filename.  An empty line is 'completed' as a filename.

       You  can  list the possible completions of a word at any time by typing '^D' to run the delete-char-or-list-or-
       eof editor command.  The shell lists the possible completions using the ls-F builtin (q.v.)  and  reprints  the
       prompt and unfinished command line, for example:

           > ls /usr/l[^D]
           lbin/       lib/        local/      lost+found/
           > ls /usr/l

       If  the  autolist  shell  variable  is  set, the shell lists the remaining choices (if any) whenever completion
       fails:

           > set autolist
           > nm /usr/lib/libt[tab]
           libtermcap.a@ libtermlib.a@
           > nm /usr/lib/libterm

       If autolist is set to 'ambiguous', choices are listed only when completion fails and adds no new characters  to
       the word being completed.

       A  filename  to  be  completed can contain variables, your own or others' home directories abbreviated with '~'
       (see Filename substitution) and directory stack entries abbreviated with '='  (see  Directory  stack  substitu-
       tion).  For example,

           > ls ~k[^D]
           kahn    kas     kellogg
           > ls ~ke[tab]
           > ls ~kellogg/

       or

           > set local = /usr/local
           > ls $lo[tab]
           > ls $local/[^D]
           bin/ etc/ lib/ man/ src/
           > ls $local/

       Note that variables can also be expanded explicitly with the expand-variables editor command.

       delete-char-or-list-or-eof  lists at only the end of the line; in the middle of a line it deletes the character
       under the cursor and on an empty line it logs one out or, if ignoreeof is set, does nothing.  'M-^D', bound  to
       the  editor  command  list-choices, lists completion possibilities anywhere on a line, and list-choices (or any
       one of the related editor commands that do or don't delete, list and/or log out, listed  under  delete-char-or-
       list-or-eof) can be bound to '^D' with the bindkey builtin command if so desired.

       The  complete-word-fwd and complete-word-back editor commands (not bound to any keys by default) can be used to
       cycle up and down through the list of possible completions, replacing the current word with the next or  previ-
       ous word in the list.

       The  shell variable fignore can be set to a list of suffixes to be ignored by completion.  Consider the follow-
       ing:

           > ls
           Makefile        condiments.h~   main.o          side.c
           README          main.c          meal            side.o
           condiments.h    main.c~
           > set fignore = (.o \~)
           > emacs ma[^D]
           main.c   main.c~  main.o
           > emacs ma[tab]
           > emacs main.c

       'main.c~' and 'main.o' are ignored by completion (but not listing), because they end in  suffixes  in  fignore.
       Note  that  a '\' was needed in front of '~' to prevent it from being expanded to home as described under File-
       name substitution.  fignore is ignored if only one completion is possible.

       If the complete shell variable is set to 'enhance', completion  1)  ignores  case  and  2)  considers  periods,
       hyphens  and underscores ('.', '-' and '_') to be word separators and hyphens and underscores to be equivalent.
       If you had the following files

           comp.lang.c      comp.lang.perl   comp.std.c++
           comp.lang.c++    comp.std.c

       and typed 'mail -f c.l.c[tab]', it would be completed to 'mail -f comp.lang.c', and ^D would list 'comp.lang.c'
       and  'comp.lang.c++'.   'mail  -f  c..c++[^D]'  would  list  'comp.lang.c++'  and  'comp.std.c++'.   Typing 'rm
       a--file[^D]' in the following directory

           A_silly_file    a-hyphenated-file    another_silly_file

       would list all three files, because case is ignored and hyphens and underscores are equivalent.  Periods,  how-
       ever, are not equivalent to hyphens or underscores.

       Completion  and  listing  are affected by several other shell variables: recexact can be set to complete on the
       shortest possible unique match, even if more typing might result in a longer match:

           > ls
           fodder   foo      food     foonly
           > set recexact
           > rm fo[tab]

       just beeps, because 'fo' could expand to 'fod' or 'foo', but if we type another 'o',

           > rm foo[tab]
           > rm foo

       the completion completes on 'foo', even though 'food' and 'foonly' also match.  autoexpand can be  set  to  run
       the  expand-history  editor  command before each completion attempt, autocorrect can be set to spelling-correct
       the word to be completed (see Spelling correction) before each completion attempt and correct  can  be  set  to
       complete  commands  automatically after one hits 'return'.  matchbeep can be set to make completion beep or not
       beep in a variety of situations, and nobeep can be set to never beep at all.  nostat can be set to  a  list  of
       directories  and/or  patterns  that match directories to prevent the completion mechanism from stat(2)ing those
       directories.  listmax and listmaxrows can be set to limit the number of items and rows (respectively) that  are
       listed  without  asking  first.   recognize_only_executables can be set to make the shell list only executables
       when listing commands, but it is quite slow.

       Finally, the complete builtin command can be used to tell the shell how to complete words other than filenames,
       commands  and  variables.  Completion and listing do not work on glob-patterns (see Filename substitution), but
       the list-glob and expand-glob editor commands perform equivalent functions for glob-patterns.

   Spelling correction (+)
       The shell can sometimes correct the spelling of filenames, commands and variable names as  well  as  completing
       and listing them.

       Individual  words  can  be spelling-corrected with the spell-word editor command (usually bound to M-s and M-S)
       and the entire input buffer with spell-line (usually bound to M-$).  The correct shell variable can be  set  to
       'cmd'  to  correct the command name or 'all' to correct the entire line each time return is typed, and autocor-
       rect can be set to correct the word to be completed before each completion attempt.

       When spelling correction is invoked in any of these ways and the shell thinks that any part of the command line
       is misspelled, it prompts with the corrected line:

           > set correct = cmd
           > lz /usr/bin
           CORRECT>ls /usr/bin (y|n|e|a)?

       One  can  answer  'y' or space to execute the corrected line, 'e' to leave the uncorrected command in the input
       buffer, 'a' to abort the command as if '^C' had been hit, and  anything  else  to  execute  the  original  line
       unchanged.

       Spelling  correction  recognizes user-defined completions (see the complete builtin command).  If an input word
       in a position for which a completion is defined resembles a word in the completion  list,  spelling  correction
       registers  a  misspelling  and  suggests  the latter word as a correction.  However, if the input word does not
       match any of the possible completions for that position, spelling correction does not register a misspelling.

       Like completion, spelling correction works anywhere in the line, pushing the rest of the line to the right  and
       possibly leaving extra characters to the right of the cursor.

       Beware: spelling correction is not guaranteed to work the way one intends, and is provided mostly as an experi-
       mental feature.  Suggestions and improvements are welcome.

   Editor commands (+)
       'bindkey' lists key bindings and 'bindkey -l' lists and briefly describes editor commands.  Only new  or  espe-
       cially  interesting  editor  commands are described here.  See emacs(1) and vi(1) for descriptions of each edi-
       tor's key bindings.

       The character or characters to which each command is bound by default is given  in  parentheses.   '^character'
       means  a control character and 'M-character' a meta character, typed as escape-character on terminals without a
       meta key.  Case counts, but commands that are bound to letters by default are bound to both lower-  and  upper-
       case letters for convenience.

       complete-word (tab)
               Completes a word as described under Completion and listing.

       complete-word-back (not bound)
               Like complete-word-fwd, but steps up from the end of the list.

       complete-word-fwd (not bound)
               Replaces  the current word with the first word in the list of possible completions.  May be repeated to
               step down through the list.  At the end of the list, beeps and reverts to the incomplete word.

       complete-word-raw (^X-tab)
               Like complete-word, but ignores user-defined completions.

       copy-prev-word (M-^_)
               Copies the previous word in the current line into the input buffer.  See also insert-last-word.

       dabbrev-expand (M-/)
               Expands the current word to the most recent preceding one for which the current is a leading substring,
               wrapping around the history list (once) if necessary.  Repeating dabbrev-expand without any intervening
               typing changes to the next previous word etc., skipping identical  matches  much  like  history-search-
               backward does.

       delete-char (not bound)
               Deletes the character under the cursor.  See also delete-char-or-list-or-eof.

       delete-char-or-eof (not bound)
               Does  delete-char  if  there is a character under the cursor or end-of-file on an empty line.  See also
               delete-char-or-list-or-eof.

       delete-char-or-list (not bound)
               Does delete-char if there is a character under the cursor or list-choices at the end of the line.   See
               also delete-char-or-list-or-eof.

       delete-char-or-list-or-eof (^D)
               Does  delete-char if there is a character under the cursor, list-choices at the end of the line or end-
               of-file on an empty line.  See also those three commands, each of which does only a single action,  and
               delete-char-or-eof,  delete-char-or-list and list-or-eof, each of which does a different two out of the
               three.

       down-history (down-arrow, ^N)
               Like up-history, but steps down, stopping at the original input line.

       end-of-file (not bound)
               Signals an end of file, causing the shell to exit unless the ignoreeof shell variable (q.v.) is set  to
               prevent this.  See also delete-char-or-list-or-eof.

       expand-history (M-space)
               Expands  history  substitutions  in the current word.  See History substitution.  See also magic-space,
               toggle-literal-history and the autoexpand shell variable.

       expand-glob (^X-*)
               Expands the glob-pattern to the left of the cursor.  See Filename substitution.

       expand-line (not bound)
               Like expand-history, but expands history substitutions in each word in the input buffer,

       expand-variables (^X-$)
               Expands the variable to the left of the cursor.  See Variable substitution.

       history-search-backward (M-p, M-P)
               Searches backwards through the history list for a command beginning with the current  contents  of  the
               input  buffer  up  to the cursor and copies it into the input buffer.  The search string may be a glob-
               pattern (see Filename substitution) containing '*', '?', '[]' or  '{}'.   up-history  and  down-history
               will  proceed  from  the  appropriate  point  in the history list.  Emacs mode only.  See also history-
               search-forward and i-search-back.

       history-search-forward (M-n, M-N)
               Like history-search-backward, but searches forward.

       i-search-back (not bound)
               Searches backward like history-search-backward, copies the first match into the input buffer  with  the
               cursor  positioned at the end of the pattern, and prompts with 'bck: ' and the first match.  Additional
               characters may be typed to extend the search, i-search-back may be typed to continue searching with the
               same  pattern,  wrapping around the history list if necessary, (i-search-back must be bound to a single
               character for this to work) or one of the following special characters may be typed:

                   ^W      Appends the rest of the word under the cursor to the search pattern.
                   delete (or any character bound to backward-delete-char)
                           Undoes the effect of the last character typed and deletes a character from the search  pat-
                           tern if appropriate.
                   ^G      If  the previous search was successful, aborts the entire search.  If not, goes back to the
                           last successful search.
                   escape  Ends the search, leaving the current line in the input buffer.

               Any other character not bound to self-insert-command terminates the search, leaving the current line in
               the input buffer, and is then interpreted as normal input.  In particular, a carriage return causes the
               current line to be executed.  Emacs mode only.  See also i-search-fwd and history-search-backward.

       i-search-fwd (not bound)
               Like i-search-back, but searches forward.

       insert-last-word (M-_)
               Inserts the last word of the previous input line ('!$') into the input  buffer.   See  also  copy-prev-
               word.

       list-choices (M-^D)
               Lists  completion  possibilities  as  described under Completion and listing.  See also delete-char-or-
               list-or-eof and list-choices-raw.

       list-choices-raw (^X-^D)
               Like list-choices, but ignores user-defined completions.

       list-glob (^X-g, ^X-G)
               Lists (via the ls-F builtin) matches to the glob-pattern (see Filename substitution) to the left of the
               cursor.

       list-or-eof (not bound)
               Does list-choices or end-of-file on an empty line.  See also delete-char-or-list-or-eof.

       magic-space (not bound)
               Expands  history  substitutions  in the current line, like expand-history, and inserts a space.  magic-
               space is designed to be bound to the space bar, but is not bound by default.

       normalize-command (^X-?)
               Searches for the current word in PATH and, if it is found, replaces it with the full path to  the  exe-
               cutable.   Special  characters are quoted.  Aliases are expanded and quoted but commands within aliases
               are not.  This command is useful with commands that take commands as arguments,  e.g.,  'dbx'  and  'sh
               -x'.

       normalize-path (^X-n, ^X-N)
               Expands the current word as described under the 'expand' setting of the symlinks shell variable.

       overwrite-mode (unbound)
               Toggles between input and overwrite modes.

       run-fg-editor (M-^Z)
               Saves the current input line and looks for a stopped job with a name equal to the last component of the
               file name part of the EDITOR or VISUAL environment variables, or, if neither is set, 'ed' or 'vi'.   If
               such  a  job is found, it is restarted as if 'fg %job' had been typed.  This is used to toggle back and
               forth between an editor and the shell easily.  Some people bind this command to '^Z'  so  they  can  do
               this even more easily.

       run-help (M-h, M-H)
               Searches  for  documentation  on the current command, using the same notion of 'current command' as the
               completion routines, and prints it.  There is no way to use a pager; run-help  is  designed  for  short
               help  files.   If  the  special alias helpcommand is defined, it is run with the command name as a sole
               argument.  Else, documentation should be in a file named command.help, command.1, command.6,  command.8
               or  command,  which  should  be in one of the directories listed in the HPATH environment variable.  If
               there is more than one help file only the first is printed.

       self-insert-command (text characters)
               In insert mode (the default), inserts the typed character into the input line after the character under
               the  cursor.  In overwrite mode, replaces the character under the cursor with the typed character.  The
               input mode is normally preserved between lines, but the inputmode shell variable can be set to 'insert'
               or  'overwrite' to put the editor in that mode at the beginning of each line.  See also overwrite-mode.

       sequence-lead-in (arrow prefix, meta prefix, ^X)
               Indicates that the following characters are part of a multi-key  sequence.   Binding  a  command  to  a
               multi-key  sequence  really creates two bindings: the first character to sequence-lead-in and the whole
               sequence to the command.  All sequences beginning with a character bound to sequence-lead-in are effec-
               tively bound to undefined-key unless bound to another command.

       spell-line (M-$)
               Attempts  to  correct the spelling of each word in the input buffer, like spell-word, but ignores words
               whose first character is one of '-', '!', '^' or '%', or which contain '\', '*' or '?', to avoid  prob-
               lems with switches, substitutions and the like.  See Spelling correction.

       spell-word (M-s, M-S)
               Attempts  to  correct  the spelling of the current word as described under Spelling correction.  Checks
               each component of a word which appears to be a pathname.

       toggle-literal-history (M-r, M-R)
               Expands or 'unexpands' history substitutions in the input buffer.   See  also  expand-history  and  the
               autoexpand shell variable.

       undefined-key (any unbound key)
               Beeps.

       up-history (up-arrow, ^P)
               Copies  the previous entry in the history list into the input buffer.  If histlit is set, uses the lit-
               eral form of the entry.  May be repeated to step up through the history list, stopping at the top.

       vi-search-back (?)
               Prompts with '?' for a search string (which may be a glob-pattern,  as  with  history-search-backward),
               searches  for  it  and  copies it into the input buffer.  The bell rings if no match is found.  Hitting
               return ends the search and leaves the last match in the input buffer.  Hitting escape ends  the  search
               and executes the match.  vi mode only.

       vi-search-fwd (/)
               Like vi-search-back, but searches forward.

       which-command (M-?)
               Does a which (see the description of the builtin command) on the first word of the input buffer.

       yank-pop (M-y)
               When  executed  immediately  after a yank or another yank-pop, replaces the yanked string with the next
               previous string from the killring. This also has the effect of rotating the killring,  such  that  this
               string  will  be  considered  the most recently killed by a later yank command. Repeating yank-pop will
               cycle through the killring any number of times.

   Lexical structure
       The shell splits input lines into words at blanks and tabs.  The special characters '&', '|',  ';',  '<',  '>',
       '(',  and  ')'  and  the doubled characters '&&', '||', '<<' and '>>' are always separate words, whether or not
       they are surrounded by whitespace.

       When the shell's input is not a terminal, the character '#' is taken to begin a comment.  Each '#' and the rest
       of the input line on which it appears is discarded before further parsing.

       A  special  character (including a blank or tab) may be prevented from having its special meaning, and possibly
       made part of another word, by preceding it with a backslash ('\') or enclosing it in single ('''), double ('"')
       or  backward (''') quotes.  When not otherwise quoted a newline preceded by a '\' is equivalent to a blank, but
       inside quotes this sequence results in a newline.

       Furthermore, all Substitutions (see below) except History  substitution  can  be  prevented  by  enclosing  the
       strings  (or  parts  of strings) in which they appear with single quotes or by quoting the crucial character(s)
       (e.g., '$' or ''' for Variable substitution or Command substitution respectively) with '\'.   (Alias  substitu-
       tion  is  no exception: quoting in any way any character of a word for which an alias has been defined prevents
       substitution of the alias.  The usual way of quoting an alias is to precede it with a backslash.) History  sub-
       stitution  is prevented by backslashes but not by single quotes.  Strings quoted with double or backward quotes
       undergo Variable substitution and Command substitution, but other substitutions are prevented.

       Text inside single or double quotes becomes a single word (or part of one).  Metacharacters in  these  strings,
       including  blanks  and  tabs,  do  not form separate words.  Only in one special case (see Command substitution
       below) can a double-quoted string yield parts of more than one word; single-quoted strings never do.   Backward
       quotes are special: they signal Command substitution (q.v.), which may result in more than one word.

       Quoting  complex  strings,  particularly strings which themselves contain quoting characters, can be confusing.
       Remember that quotes need not be used as they are in human writing!  It may be easier to quote  not  an  entire
       string,  but  only  those  parts of the string which need quoting, using different types of quoting to do so if
       appropriate.

       The backslash_quote shell variable (q.v.) can be set to make backslashes always quote '\', ''', and  '"'.   (+)
       This may make complex quoting tasks easier, but it can cause syntax errors in csh(1) scripts.

   Substitutions
       We  now  describe the various transformations the shell performs on the input in the order in which they occur.
       We note in passing the data structures involved and the commands and variables  which  affect  them.   Remember
       that substitutions can be prevented by quoting as described under Lexical structure.

   History substitution
       Each  command,  or  ''event'',  input  from the terminal is saved in the history list.  The previous command is
       always saved, and the history shell variable can be set to a number to save that many  commands.   The  histdup
       shell variable can be set to not save duplicate events or consecutive duplicate events.

       Saved  commands are numbered sequentially from 1 and stamped with the time.  It is not usually necessary to use
       event numbers, but the current event number can be made part of the prompt by placing  an  '!'  in  the  prompt
       shell variable.

       The  shell actually saves history in expanded and literal (unexpanded) forms.  If the histlit shell variable is
       set, commands that display and store history use the literal form.

       The history builtin command can print, store in a file, restore and clear the history list at any time, and the
       savehist  and  histfile shell variables can be can be set to store the history list automatically on logout and
       restore it on login.

       History substitutions introduce words from the history list into the input stream, making  it  easy  to  repeat
       commands, repeat arguments of a previous command in the current command, or fix spelling mistakes in the previ-
       ous command with little typing and a high degree of confidence.

       History substitutions begin with the character '!'.  They may begin anywhere in the input stream, but  they  do
       not  nest.   The  '!' may be preceded by a '\' to prevent its special meaning; for convenience, a '!' is passed
       unchanged when it is followed by a blank, tab, newline, '=' or '('.  History substitutions also occur  when  an
       input  line begins with '^'.  This special abbreviation will be described later.  The characters used to signal
       history substitution ('!' and '^') can be changed by setting the histchars  shell  variable.   Any  input  line
       which contains a history substitution is printed before it is executed.

       A  history  substitution may have an ''event specification'', which indicates the event from which words are to
       be taken, a ''word designator'', which selects particular words from the chosen event, and/or  a  ''modifier'',
       which manipulates the selected words.

       An event specification can be

           n       A number, referring to a particular event
           -n      An offset, referring to the event n before the current event
           #       The current event.  This should be used carefully in csh(1), where there is no check for recursion.
                   tcsh allows 10 levels of recursion.  (+)
           !       The previous event (equivalent to '-1')
           s       The most recent event whose first word begins with the string s
           ?s?     The most recent event which contains the string s.  The second '?' can be omitted if it is  immedi-
                   ately followed by a newline.

       For example, consider this bit of someone's history list:

            9  8:30    nroff -man wumpus.man
           10  8:31    cp wumpus.man wumpus.man.old
           11  8:36    vi wumpus.man
           12  8:37    diff wumpus.man.old wumpus.man

       The  commands are shown with their event numbers and time stamps.  The current event, which we haven't typed in
       yet, is event 13.  '!11' and '!-2' refer to event 11.  '!!' refers to the previous  event,  12.   '!!'  can  be
       abbreviated  '!'  if it is followed by ':' (':' is described below).  '!n' refers to event 9, which begins with
       'n'.  '!?old?' also refers to event 12, which contains 'old'.  Without word designators  or  modifiers  history
       references  simply  expand to the entire event, so we might type '!cp' to redo the copy command or '!!|more' if
       the 'diff' output scrolled off the top of the screen.

       History references may be insulated from the surrounding text with braces if necessary.  For  example,  '!vdoc'
       would  look for a command beginning with 'vdoc', and, in this example, not find one, but '!{v}doc' would expand
       unambiguously to 'vi wumpus.mandoc'.  Even in braces, history substitutions do not nest.

       (+) While csh(1) expands, for example, '!3d' to event 3 with the letter 'd' appended to it, tcsh expands it  to
       the last event beginning with '3d'; only completely numeric arguments are treated as event numbers.  This makes
       it possible to recall events beginning with numbers.  To expand '!3d' as in csh(1) say '!{3}d'.

       To select words from an event we can follow the event specification by a ':' and a designator for  the  desired
       words.   The  words  of an input line are numbered from 0, the first (usually command) word being 0, the second
       word (first argument) being 1, etc.  The basic word designators are:

           0       The first (command) word
           n       The nth argument
           ^       The first argument, equivalent to '1'
           $       The last argument
           %       The word matched by an ?s? search
           x-y     A range of words
           -y      Equivalent to '0-y'
           *       Equivalent to '^-$', but returns nothing if the event contains only 1 word
           x*      Equivalent to 'x-$'
           x-      Equivalent to 'x*', but omitting the last word ('$')

       Selected words are inserted into the command line separated by single blanks.  For example, the 'diff'  command
       in  the previous example might have been typed as 'diff !!:1.old !!:1' (using ':1' to select the first argument
       from the previous event) or 'diff !-2:2 !-2:1' to select and swap the arguments from the 'cp' command.   If  we
       didn't  care  about the order of the 'diff' we might have said 'diff !-2:1-2' or simply 'diff !-2:*'.  The 'cp'
       command might have been written 'cp wumpus.man !#:1.old', using '#' to  refer  to  the  current  event.   '!n:-
       hurkle.man' would reuse the first two words from the 'nroff' command to say 'nroff -man hurkle.man'.

       The  ':'  separating  the  event specification from the word designator can be omitted if the argument selector
       begins with a '^', '$', '*', '%' or '-'.  For example, our 'diff' command might have been  'diff  !!^.old  !!^'
       or, equivalently, 'diff !!$.old !!$'.  However, if '!!' is abbreviated '!', an argument selector beginning with
       '-' will be interpreted as an event specification.

       A history reference may have a word designator but no event specification.  It  then  references  the  previous
       command.  Continuing our 'diff' example, we could have said simply 'diff !^.old !^' or, to get the arguments in
       the opposite order, just 'diff !*'.

       The word or words in a history reference can be edited, or ''modified'', by following it with one or more modi-
       fiers, each preceded by a ':':

           h       Remove a trailing pathname component, leaving the head.
           t       Remove all leading pathname components, leaving the tail.
           r       Remove a filename extension '.xxx', leaving the root name.
           e       Remove all but the extension.
           u       Uppercase the first lowercase letter.
           l       Lowercase the first uppercase letter.
           s/l/r/  Substitute  l  for  r.   l  is simply a string like r, not a regular expression as in the eponymous
                   ed(1) command.  Any character may be used as the delimiter in place of '/'; a '\' can  be  used  to
                   quote  the  delimiter  expect  '(', ')', '|' and '>' inside l and r.  The character '&' in the r is
                   replaced by l; '\' also quotes '&'.  If l is empty (''''), the l from a  previous  substitution  or
                   the  s  from a previous search or event number in event specification is used.  The trailing delim-
                   iter may be omitted if it is immediately followed by a newline.
           &       Repeat the previous substitution.
           g       Apply the following modifier once to each word.
           a (+)   Apply the following modifier as many times as possible to a single word.  'a' and 'g' can  be  used
                   together  to  apply a modifier globally.  With the 's' modifier, only the patterns contained in the
                   original word are substituted, not patterns that contain any substitution result.
           p       Print the new command line but do not execute it.
           q       Quote the substituted words, preventing further substitutions.
           x       Like q, but break into words at blanks, tabs and newlines.

       Modifiers are applied to only the first modifiable word (unless 'g' is used).  It is an error for no word to be
       modifiable.

       For  example,  the  'diff' command might have been written as 'diff wumpus.man.old !#^:r', using ':r' to remove
       '.old' from the first argument on the same line ('!#^').  We could say 'echo hello out there', then 'echo !*:u'
       to  capitalize  'hello',  'echo  !*:au'  to say it out loud, or 'echo !*:agu' to really shout.  We might follow
       'mail -s "I forgot my password" rot' with '!:s/rot/root' to correct the spelling of 'root'  (but  see  Spelling
       correction for a different approach).

       There  is  a  special abbreviation for substitutions.  '^', when it is the first character on an input line, is
       equivalent to '!:s^'.  Thus we might have said '^rot^root' to make the  spelling  correction  in  the  previous
       example.  This is the only history substitution which does not explicitly begin with '!'.

       (+) In csh as such, only one modifier may be applied to each history or variable expansion.  In tcsh, more than
       one may be used, for example

           % mv wumpus.man /usr/man/man1/wumpus.1
           % man !$:t:r
           man wumpus

       In csh, the result would be 'wumpus.1:r'.  A substitution followed by a colon may need to be insulated from  it
       with braces:

           > mv a.out /usr/games/wumpus
           > setenv PATH !$:h:$PATH
           Bad ! modifier: $.
           > setenv PATH !{-2$:h}:$PATH
           setenv PATH /usr/games:/bin:/usr/bin:.

       The  first attempt would succeed in csh but fails in tcsh, because tcsh expects another modifier after the sec-
       ond colon rather than '$'.

       Finally, history can be accessed through the editor as well as through the substitutions just  described.   The
       up-  and  down-history,  history-search-backward and -forward, i-search-back and -fwd, vi-search-back and -fwd,
       copy-prev-word and insert-last-word editor commands search for events in the history list and  copy  them  into
       the input buffer.  The toggle-literal-history editor command switches between the expanded and literal forms of
       history lines in the input buffer.  expand-history and expand-line expand history substitutions in the  current
       word and in the entire input buffer respectively.

   Alias substitution
       The  shell  maintains  a list of aliases which can be set, unset and printed by the alias and unalias commands.
       After a command line is parsed into simple commands (see Commands) the first word  of  each  command,  left-to-
       right,  is  checked  to  see if it has an alias.  If so, the first word is replaced by the alias.  If the alias
       contains a history reference, it undergoes History substitution (q.v.) as though the original command were  the
       previous input line.  If the alias does not contain a history reference, the argument list is left untouched.

       Thus if the alias for 'ls' were 'ls -l' the command 'ls /usr' would become 'ls -l /usr', the argument list here
       being undisturbed.  If the alias for 'lookup' were 'grep !^ /etc/passwd' then 'lookup bill' would become  'grep
       bill  /etc/passwd'.   Aliases  can be used to introduce parser metasyntax.  For example, 'alias print 'pr \!* |
       lpr'' defines a ''command'' ('print') which pr(1)s its arguments to the line printer.

       Alias substitution is repeated until the first word of the command has no alias.  If an alias substitution does
       not  change  the  first  word  (as  in  the previous example) it is flagged to prevent a loop.  Other loops are
       detected and cause an error.

       Some aliases are referred to by the shell; see Special aliases.

   Variable substitution
       The shell maintains a list of variables, each of which has as value a list of zero or more words.   The  values
       of  shell variables can be displayed and changed with the set and unset commands.  The system maintains its own
       list of ''environment'' variables.  These can be displayed and changed with printenv, setenv and unsetenv.

       (+) Variables may be made read-only with 'set -r' (q.v.)  Read-only variables may not  be  modified  or  unset;
       attempting  to do so will cause an error.  Once made read-only, a variable cannot be made writable, so 'set -r'
       should be used with caution.  Environment variables cannot be made read-only.

       Some variables are set by the shell or referred to by it.  For instance, the argv variable is an image  of  the
       shell's  argument  list, and words of this variable's value are referred to in special ways.  Some of the vari-
       ables referred to by the shell are toggles; the shell does not care what their value is, only whether they  are
       set  or  not.   For instance, the verbose variable is a toggle which causes command input to be echoed.  The -v
       command line option sets this variable.  Special shell variables lists all variables which are referred  to  by
       the shell.

       Other operations treat variables numerically.  The '@' command permits numeric calculations to be performed and
       the result assigned to a variable.  Variable values are, however, always represented as (zero or more) strings.
       For the purposes of numeric operations, the null string is considered to be zero, and the second and subsequent
       words of multi-word values are ignored.

       After the input line is aliased and parsed, and before each command is executed, variable substitution is  per-
       formed  keyed by '$' characters.  This expansion can be prevented by preceding the '$' with a '\' except within
       '"'s where it always occurs, and within '''s where it never occurs.  Strings  quoted  by  '''  are  interpreted
       later  (see Command substitution below) so '$' substitution does not occur there until later, if at all.  A '$'
       is passed unchanged if followed by a blank, tab, or end-of-line.

       Input/output redirections are recognized before variable expansion, and are variable expanded separately.  Oth-
       erwise,  the  command  name  and entire argument list are expanded together.  It is thus possible for the first
       (command) word (to this point) to generate more than one word, the first of which becomes the command name, and
       the rest of which become arguments.

       Unless  enclosed  in '"' or given the ':q' modifier the results of variable substitution may eventually be com-
       mand and filename substituted.  Within '"', a variable whose value consists of  multiple  words  expands  to  a
       (portion of a) single word, with the words of the variable's value separated by blanks.  When the ':q' modifier
       is applied to a substitution the variable will expand to multiple words with each word separated by a blank and
       quoted to prevent later command or filename substitution.

       The  following  metasequences  are  provided  for  introducing variable values into the shell input.  Except as
       noted, it is an error to reference a variable which is not set.

       $name
       ${name} Substitutes the words of the value of variable name, each separated by a blank.  Braces  insulate  name
               from  following  characters which would otherwise be part of it.  Shell variables have names consisting
               of letters and digits starting with a letter.  The underscore character is  considered  a  letter.   If
               name  is  not a shell variable, but is set in the environment, then that value is returned (but some of
               the other forms given below are not available in this case).
       $name[selector]
       ${name[selector]}
               Substitutes only the selected words from the value of name.  The selector is subjected to '$' substitu-
               tion  and  may consist of a single number or two numbers separated by a '-'.  The first word of a vari-
               able's value is numbered '1'.  If the first number of a range is omitted it defaults to  '1'.   If  the
               last  member of a range is omitted it defaults to '$#name'.  The selector '*' selects all words.  It is
               not an error for a range to be empty if the second argument is omitted or in range.
       $0      Substitutes the name of the file from which command input is being read.  An error occurs if  the  name
               is not known.
       $number
       ${number}
               Equivalent to '$argv[number]'.
       $*      Equivalent to '$argv', which is equivalent to '$argv[*]'.

       The  ':'  modifiers  described under History substitution, except for ':p', can be applied to the substitutions
       above.  More than one may be used.  (+) Braces may be needed to insulate a variable substitution from a literal
       colon just as with History substitution (q.v.); any modifiers must appear within the braces.

       The following substitutions can not be modified with ':' modifiers.

       $?name
       ${?name}
               Substitutes the string '1' if name is set, '0' if it is not.
       $?0     Substitutes  '1'  if  the current input filename is known, '0' if it is not.  Always '0' in interactive
               shells.
       $#name
       ${#name}
               Substitutes the number of words in name.
       $#      Equivalent to '$#argv'.  (+)
       $%name
       ${%name}
               Substitutes the number of characters in name.  (+)
       $%number
       ${%number}
               Substitutes the number of characters in $argv[number].  (+)
       $?      Equivalent to '$status'.  (+)
       $$      Substitutes the (decimal) process number of the (parent) shell.
       $!      Substitutes the (decimal) process number of the last background process started by this shell.  (+)
       $_      Substitutes the command line of the last command executed.  (+)
       $<      Substitutes a line from the standard input, with no further interpretation thereafter.  It can be  used
               to  read from the keyboard in a shell script.  (+) While csh always quotes $<, as if it were equivalent
               to '$<:q', tcsh does not.  Furthermore, when tcsh is waiting for a line to be typed the user  may  type
               an interrupt to interrupt the sequence into which the line is to be substituted, but csh does not allow
               this.

       The editor command expand-variables, normally bound to '^X-$', can be used to interactively  expand  individual
       variables.

   Command, filename and directory stack substitution
       The remaining substitutions are applied selectively to the arguments of builtin commands.  This means that por-
       tions of expressions which are not evaluated are not subjected to these expansions.  For commands which are not
       internal  to  the  shell,  the command name is substituted separately from the argument list.  This occurs very
       late, after input-output redirection is performed, and in a child of the main shell.

   Command substitution
       Command substitution is indicated by a command enclosed in '''.  The output from such a command is broken  into
       separate  words at blanks, tabs and newlines, and null words are discarded.  The output is variable and command
       substituted and put in place of the original string.

       Command substitutions inside double quotes ('"') retain blanks and tabs; only newlines force  new  words.   The
       single  final newline does not force a new word in any case.  It is thus possible for a command substitution to
       yield only part of a word, even if the command outputs a complete line.

       By default, the shell since version 6.12 replaces all newline and carriage return characters in the command  by
       spaces.  If this is switched off by unsetting csubstnonl, newlines separate commands as usual.

   Filename substitution
       If  a  word contains any of the characters '*', '?', '[' or '{' or begins with the character '~' it is a candi-
       date for filename substitution, also known as ''globbing''.  This word is then regarded as a  pattern  (''glob-
       pattern''), and replaced with an alphabetically sorted list of file names which match the pattern.

       In matching filenames, the character '.' at the beginning of a filename or immediately following a '/', as well
       as the character '/' must be matched explicitly.  The character '*' matches any string of characters, including
       the  null string.  The character '?' matches any single character.  The sequence '[...]' matches any one of the
       characters enclosed.  Within '[...]', a pair of characters separated by '-'  matches  any  character  lexically
       between the two.

       (+)  Some glob-patterns can be negated: The sequence '[^...]' matches any single character not specified by the
       characters and/or ranges of characters in the braces.

       An entire glob-pattern can also be negated with '^':

           > echo *
           bang crash crunch ouch
           > echo ^cr*
           bang ouch

       Glob-patterns which do not use '?', '*', or '[]' or which use '{}' or '~' (below) are not negated correctly.

       The  metanotation  'a{b,c,d}e'  is  a  shorthand  for  'abe  ace  ade'.   Left-to-right  order  is   preserved:
       '/usr/source/s1/{oldls,ls}.c'  expands to '/usr/source/s1/oldls.c /usr/source/s1/ls.c'.  The results of matches
       are sorted separately at a low level to preserve this order: '../{memo,*box}' might expand to  '../memo  ../box
       ../mbox'.  (Note that 'memo' was not sorted with the results of matching '*box'.)  It is not an error when this
       construct expands to files which do not exist, but it is possible to get an error from a command to  which  the
       expanded  list  is  passed.   This  construct may be nested.  As a special case the words '{', '}' and '{}' are
       passed undisturbed.

       The character '~' at the beginning of a filename refers to home directories.  Standing  alone,  i.e.,  '~',  it
       expands to the invoker's home directory as reflected in the value of the home shell variable.  When followed by
       a name consisting of letters, digits and '-' characters the shell searches for a user with that name  and  sub-
       stitutes  their  home directory; thus '~ken' might expand to '/usr/ken' and '~ken/chmach' to '/usr/ken/chmach'.
       If the character '~' is followed by a character other than a letter or '/' or appears  elsewhere  than  at  the
       beginning of a word, it is left undisturbed.  A command like 'setenv MANPATH /usr/man:/usr/local/man:~/lib/man'
       does not, therefore, do home directory substitution as one might hope.

       It is an error for a glob-pattern containing '*', '?', '[' or '~', with or without '^', not to match any files.
       However,  only  one pattern in a list of glob-patterns must match a file (so that, e.g., 'rm *.a *.c *.o' would
       fail only if there were no files in the current directory ending in '.a', '.c', or '.o'), and if the  nonomatch
       shell variable is set a pattern (or list of patterns) which matches nothing is left unchanged rather than caus-
       ing an error.

       The noglob shell variable can be set to prevent filename substitution, and the expand-glob editor command, nor-
       mally bound to '^X-*', can be used to interactively expand individual filename substitutions.

   Directory stack substitution (+)
       The directory stack is a list of directories, numbered from zero, used by the pushd, popd and dirs builtin com-
       mands (q.v.).  dirs can print, store in a file, restore and clear the directory stack  at  any  time,  and  the
       savedirs  and  dirsfile  shell  variables  can  be set to store the directory stack automatically on logout and
       restore it on login.  The dirstack shell variable can be examined to see the directory stack  and  set  to  put
       arbitrary directories into the directory stack.

       The  character '=' followed by one or more digits expands to an entry in the directory stack.  The special case
       '=-' expands to the last directory in the stack.  For example,

           > dirs -v
           0       /usr/bin
           1       /usr/spool/uucp
           2       /usr/accts/sys
           > echo =1
           /usr/spool/uucp
           > echo =0/calendar
           /usr/bin/calendar
           > echo =-
           /usr/accts/sys

       The noglob and nonomatch shell variables and the expand-glob editor command apply to directory stack as well as
       filename substitutions.

   Other substitutions (+)
       There  are  several  more  transformations involving filenames, not strictly related to the above but mentioned
       here for completeness.  Any filename may be expanded to a full path when the symlinks variable (q.v.) is set to
       'expand'.   Quoting prevents this expansion, and the normalize-path editor command does it on demand.  The nor-
       malize-command editor command expands commands in PATH into full paths on demand.  Finally, cd and pushd inter-
       pret  '-'  as  the old working directory (equivalent to the shell variable owd).  This is not a substitution at
       all, but an abbreviation recognized by only those commands.  Nonetheless, it too can be prevented by quoting.

   Commands
       The next three sections describe how the shell executes commands and deals with their input and output.

   Simple commands, pipelines and sequences
       A simple command is a sequence of words, the first of which specifies the command to be executed.  A series  of
       simple  commands  joined  by '|' characters forms a pipeline.  The output of each command in a pipeline is con-
       nected to the input of the next.

       Simple commands and pipelines may be joined into sequences with ';', and will be executed  sequentially.   Com-
       mands and pipelines can also be joined into sequences with '||' or '&&', indicating, as in the C language, that
       the second is to be executed only if the first fails or succeeds respectively.

       A simple command, pipeline or sequence may be placed in parentheses, '()', to form a simple command, which  may
       in  turn  be  a  component  of a pipeline or sequence.  A command, pipeline or sequence can be executed without
       waiting for it to terminate by following it with an '&'.

   Builtin and non-builtin command execution
       Builtin commands are executed within the shell.  If any component of a pipeline except the last  is  a  builtin
       command, the pipeline is executed in a subshell.

       Parenthesized commands are always executed in a subshell.

           (cd; pwd); pwd

       thus prints the home directory, leaving you where you were (printing this after the home directory), while

           cd; pwd

       leaves  you in the home directory.  Parenthesized commands are most often used to prevent cd from affecting the
       current shell.

       When a command to be executed is found not to be a builtin command the shell attempts to  execute  the  command
       via  execve(2).  Each word in the variable path names a directory in which the shell will look for the command.
       If the shell is not given a -f option, the shell hashes the names in these directories into an  internal  table
       so  that  it  will  try  an execve(2) in only a directory where there is a possibility that the command resides
       there.  This greatly speeds command location when a large number of directories are present in the search path.
       This hashing mechanism is not used:

       1.  If hashing is turned explicitly off via unhash.

       2.  If the shell was given a -f argument.

       3.  For each directory component of path which does not begin with a '/'.

       4.  If the command contains a '/'.

       In the above four cases the shell concatenates each component of the path vector with the given command name to
       form a path name of a file which it then attempts to execute it. If execution is successful, the search  stops.

       If  the  file has execute permissions but is not an executable to the system (i.e., it is neither an executable
       binary nor a script that specifies its interpreter), then it is assumed to be a file containing shell  commands
       and a new shell is spawned to read it.  The shell special alias may be set to specify an interpreter other than
       the shell itself.

       On systems which do not understand the '#!' script interpreter convention the shell may be compiled to  emulate
       it;  see the version shell variable.  If so, the shell checks the first line of the file to see if it is of the
       form '#!interpreter arg ...'.  If it is, the shell starts interpreter with the given args and feeds the file to
       it on standard input.

   Input/output
       The standard input and standard output of a command may be redirected with the following syntax:

       < name  Open file name (which is first variable, command and filename expanded) as the standard input.
       << word Read the shell input up to a line which is identical to word.  word is not subjected to variable, file-
               name or command substitution, and each input line is compared to word before any substitutions are done
               on  this input line.  Unless a quoting '\', '"', '' or ''' appears in word variable and command substi-
               tution is performed on the intervening lines, allowing '\' to quote '$', '\' and '''.   Commands  which
               are  substituted  have  all blanks, tabs, and newlines preserved, except for the final newline which is
               dropped.  The resultant text is placed in an anonymous temporary file which is given to the command  as
               standard input.
       > name
       >! name
       >& name
       >&! name
               The  file  name is used as standard output.  If the file does not exist then it is created; if the file
               exists, it is truncated, its previous contents being lost.

               If the shell variable noclobber is set, then the file must not exist or be  a  character  special  file
               (e.g.,  a  terminal  or '/dev/null') or an error results.  This helps prevent accidental destruction of
               files.  In this case the '!' forms can be used to suppress this check.

               The forms involving '&' route the diagnostic output into the specified file as  well  as  the  standard
               output.  name is expanded in the same way as '<' input filenames are.
       >> name
       >>& name
       >>! name
       >>&! name
               Like '>', but appends output to the end of name.  If the shell variable noclobber is set, then it is an
               error for the file not to exist, unless one of the '!' forms is given.

       A command receives the environment in which the shell was invoked as modified by  the  input-output  parameters
       and  the presence of the command in a pipeline.  Thus, unlike some previous shells, commands run from a file of
       shell commands have no access to the text of the commands by default; rather they receive the original standard
       input  of  the  shell.   The  '<<' mechanism should be used to present inline data.  This permits shell command
       scripts to function as components of pipelines and allows the shell to block read its  input.   Note  that  the
       default  standard  input  for a command run detached is not the empty file /dev/null, but the original standard
       input of the shell.  If this is a terminal and if the process attempts to read from the terminal, then the pro-
       cess will block and the user will be notified (see Jobs).

       Diagnostic  output  may  be  directed through a pipe with the standard output.  Simply use the form '|&' rather
       than just '|'.

       The shell cannot presently redirect diagnostic output without also redirecting standard output, but '(command >
       output-file)  >&  error-file'  is  often  an  acceptable  workaround.   Either output-file or error-file may be
       '/dev/tty' to send output to the terminal.

   Features
       Having described how the shell accepts, parses and executes command lines, we now turn to a variety of its use-
       ful features.

   Control flow
       The  shell  contains  a  number  of commands which can be used to regulate the flow of control in command files
       (shell scripts) and (in limited but useful ways) from terminal input.  These commands all  operate  by  forcing
       the  shell to reread or skip in its input and, due to the implementation, restrict the placement of some of the
       commands.

       The foreach, switch, and while statements, as well as the if-then-else form of the if statement,  require  that
       the major keywords appear in a single simple command on an input line as shown below.

       If  the  shell's  input  is not seekable, the shell buffers up input whenever a loop is being read and performs
       seeks in this internal buffer to accomplish the rereading implied by  the  loop.   (To  the  extent  that  this
       allows, backward gotos will succeed on non-seekable inputs.)

   Expressions
       The  if, while and exit builtin commands use expressions with a common syntax.  The expressions can include any
       of the operators described in the next three sections.  Note that the @ builtin command (q.v.) has its own sep-
       arate syntax.

   Logical, arithmetical and comparison operators
       These operators are similar to those of C and have the same precedence.  They include

           ||  &&  |  ^  &  ==  !=  =~  !~  <=  >=
           <  > <<  >>  +  -  *  /  %  !  ~  (  )

       Here  the precedence increases to the right, '==' '!=' '=~' and '!~', '<=' '>=' '<' and '>', '<<' and '>>', '+'
       and '-', '*' '/' and '%' being, in groups, at the same level.  When multiple operators which have  same  prece-
       dence are used in one expression, calculation must be done from operator of right side.  The '==' '!=' '=~' and
       '!~' operators compare their arguments as strings; all others operate on numbers.  The operators '=~' and  '!~'
       are  like  '!='  and '==' except that the right hand side is a glob-pattern (see Filename substitution) against
       which the left hand operand is matched.  This reduces the need for use of the switch builtin command  in  shell
       scripts when all that is really needed is pattern matching.

       Null or missing arguments are considered '0'.  The results of all expressions are strings, which represent dec-
       imal numbers.  It is important to note that no two components of an expression can appear  in  the  same  word;
       except  when  adjacent  to components of expressions which are syntactically significant to the parser ('&' '|'
       '<' '>' '(' ')') they should be surrounded by spaces.

   Command exit status
       Commands can be executed in expressions and their exit status returned by  enclosing  them  in  braces  ('{}').
       Remember  that the braces should be separated from the words of the command by spaces.  Command executions suc-
       ceed, returning true, i.e., '1', if the command exits with status 0,  otherwise  they  fail,  returning  false,
       i.e.,  '0'.   If more detailed status information is required then the command should be executed outside of an
       expression and the status shell variable examined.

   File inquiry operators
       Some of these operators perform true/false tests on files and related objects.  They are of the form -op  file,
       where op is one of

           r   Read access
           w   Write access
           x   Execute access
           X   Executable  in  the  path  or  shell  builtin,  e.g., '-X ls' and '-X ls-F' are generally true, but '-X
               /bin/ls' is not (+)
           e   Existence
           o   Ownership
           z   Zero size
           s   Non-zero size (+)
           f   Plain file
           d   Directory
           l   Symbolic link (+) *
           b   Block special file (+)
           c   Character special file (+)
           p   Named pipe (fifo) (+) *
           S   Socket special file (+) *
           u   Set-user-ID bit is set (+)
           g   Set-group-ID bit is set (+)
           k   Sticky bit is set (+)
           t   file (which must be a digit) is an open file descriptor for a terminal device (+)
           R   Has been migrated (convex only) (+)
           L   Applies subsequent operators in a multiple-operator test to a symbolic link rather than to the file  to
               which the link points (+) *

       file  is  command and filename expanded and then tested to see if it has the specified relationship to the real
       user.  If file does not exist or is inaccessible or, for the operators indicated by '*', if the specified  file
       type does not exist on the current system, then all enquiries return false, i.e., '0'.

       These  operators  may  be  combined for conciseness: '-xy file' is equivalent to '-x file && -y file'.  (+) For
       example, '-fx' is true (returns '1') for plain executable files, but not for directories.

       L may be used in a multiple-operator test to apply subsequent operators to a symbolic link rather than  to  the
       file  to  which the link points.  For example, '-lLo' is true for links owned by the invoking user.  Lr, Lw and
       Lx are always true for links and false for non-links.  L has a different meaning when it is the  last  operator
       in a multiple-operator test; see below.

       It  is  possible  but not useful, and sometimes misleading, to combine operators which expect file to be a file
       with operators which do not, (e.g., X and t).  Following L with a non-file operator can  lead  to  particularly
       strange results.

       Other  operators return other information, i.e., not just '0' or '1'.  (+) They have the same format as before;
       op may be one of

           A       Last file access time, as the number of seconds since the epoch
           A:      Like A, but in timestamp format, e.g., 'Fri May 14 16:36:10 1993'
           M       Last file modification time
           M:      Like M, but in timestamp format
           C       Last inode modification time
           C:      Like C, but in timestamp format
           D       Device number
           I       Inode number
           F       Composite file identifier, in the form device:inode
           L       The name of the file pointed to by a symbolic link
           N       Number of (hard) links
           P       Permissions, in octal, without leading zero
           P:      Like P, with leading zero
           Pmode   Equivalent to '-P file & mode', e.g., '-P22 file' returns '22' if file is  writable  by  group  and
                   other, '20' if by group only, and '0' if by neither
           Pmode:  Like Pmode, with leading zero
           U       Numeric userid
           U:      Username, or the numeric userid if the username is unknown
           G       Numeric groupid
           G:      Groupname, or the numeric groupid if the groupname is unknown
           Z       Size, in bytes

       Only one of these operators may appear in a multiple-operator test, and it must be the last.  Note that L has a
       different meaning at the end of and elsewhere in a multiple-operator test.  Because '0' is a valid return value
       for many of these operators, they do not return '0' when they fail: most return '-1', and F returns ':'.

       If  the  shell is compiled with POSIX defined (see the version shell variable), the result of a file inquiry is
       based on the permission bits of the file and not on the result of the access(2) system call.  For  example,  if
       one tests a file with -w whose permissions would ordinarily allow writing but which is on a file system mounted
       read-only, the test will succeed in a POSIX shell but fail in a non-POSIX shell.

       File inquiry operators can also be evaluated with the filetest builtin command (q.v.) (+).

   Jobs
       The shell associates a job with each pipeline.  It keeps a table of current jobs, printed by the jobs  command,
       and assigns them small integer numbers.  When a job is started asynchronously with '&', the shell prints a line
       which looks like

           [1] 1234

       indicating that the job which was started asynchronously was job number 1  and  had  one  (top-level)  process,
       whose process id was 1234.

       If  you are running a job and wish to do something else you may hit the suspend key (usually '^Z'), which sends
       a STOP signal to the current job.  The shell will then normally indicate that the job has been 'Suspended'  and
       print  another  prompt.   If  the listjobs shell variable is set, all jobs will be listed like the jobs builtin
       command; if it is set to 'long' the listing will be in long format, like 'jobs -l'.  You  can  then  manipulate
       the  state  of  the  suspended job.  You can put it in the ''background'' with the bg command or run some other
       commands and eventually bring the job back into the ''foreground'' with fg.  (See also the run-fg-editor editor
       command.)  A '^Z' takes effect immediately and is like an interrupt in that pending output and unread input are
       discarded when it is typed.  The wait builtin command causes the shell to wait for all background jobs to  com-
       plete.

       The  '^]' key sends a delayed suspend signal, which does not generate a STOP signal until a program attempts to
       read(2) it, to the current job.  This can usefully be typed ahead when you have prepared some  commands  for  a
       job  which  you  wish  to stop after it has read them.  The '^Y' key performs this function in csh(1); in tcsh,
       '^Y' is an editing command.  (+)

       A job being run in the background stops if it tries to read from the terminal.  Background  jobs  are  normally
       allowed  to  produce output, but this can be disabled by giving the command 'stty tostop'.  If you set this tty
       option, then background jobs will stop when they try to produce output like they  do  when  they  try  to  read
       input.

       There are several ways to refer to jobs in the shell.  The character '%' introduces a job name.  If you wish to
       refer to job number 1, you can name it as '%1'.  Just naming a job brings it to the foreground; thus '%1' is  a
       synonym  for  'fg  %1', bringing job 1 back into the foreground.  Similarly, saying '%1 &' resumes job 1 in the
       background, just like 'bg %1'.  A job can also be named by an unambiguous prefix of  the  string  typed  in  to
       start  it:  '%ex' would normally restart a suspended ex(1) job, if there were only one suspended job whose name
       began with the string 'ex'.  It is also possible to say '%?string' to specify a job whose text contains string,
       if there is only one such job.

       The  shell  maintains a notion of the current and previous jobs.  In output pertaining to jobs, the current job
       is marked with a '+' and the previous job with a '-'.  The abbreviations '%+', '%', and (by  analogy  with  the
       syntax of the history mechanism) '%%' all refer to the current job, and '%-' refers to the previous job.

       The  job  control  mechanism  requires that the stty(1) option 'new' be set on some systems.  It is an artifact
       from a 'new' implementation of the tty driver which allows generation of interrupt characters from the keyboard
       to  tell jobs to stop.  See stty(1) and the setty builtin command for details on setting options in the new tty
       driver.

   Status reporting
       The shell learns immediately whenever a process changes state.  It normally informs you whenever a job  becomes
       blocked  so  that  no  further progress is possible, but only right before it prints a prompt.  This is done so
       that it does not otherwise disturb your work.  If, however, you set the shell variable notify, the  shell  will
       notify  you  immediately  of  changes of status in background jobs.  There is also a shell command notify which
       marks a single process so that its status changes will be immediately reported.  By default  notify  marks  the
       current process; simply say 'notify' after starting a background job to mark it.

       When you try to leave the shell while jobs are stopped, you will be warned that 'There are suspended jobs.' You
       may use the jobs command to see what they are.  If you do this or immediately try to exit again, the shell will
       not warn you a second time, and the suspended jobs will be terminated.

   Automatic, periodic and timed events (+)
       There  are  various  ways  to  run commands and take other actions automatically at various times in the ''life
       cycle'' of the shell.  They are summarized here, and described in detail under  the  appropriate  Builtin  com-
       mands, Special shell variables and Special aliases.

       The sched builtin command puts commands in a scheduled-event list, to be executed by the shell at a given time.

       The beepcmd, cwdcmd, periodic, precmd, postcmd, and jobcmd Special aliases can be set, respectively, to execute
       commands  when  the  shell  wants  to ring the bell, when the working directory changes, every tperiod minutes,
       before each prompt, before each command gets executed, after each command gets executed,  and  when  a  job  is
       started or is brought into the foreground.

       The  autologout shell variable can be set to log out or lock the shell after a given number of minutes of inac-
       tivity.

       The mail shell variable can be set to check for new mail periodically.

       The printexitvalue shell variable can be set to print the exit status of commands  which  exit  with  a  status
       other than zero.

       The rmstar shell variable can be set to ask the user, when 'rm *' is typed, if that is really what was meant.

       The time shell variable can be set to execute the time builtin command after the completion of any process that
       takes more than a given number of CPU seconds.

       The watch and who shell variables can be set to report when selected users log in or out, and the  log  builtin
       command reports on those users at any time.

   Native Language System support (+)
       The  shell is eight bit clean (if so compiled; see the version shell variable) and thus supports character sets
       needing this capability.  NLS support differs depending on whether or not the shell was  compiled  to  use  the
       system's  NLS (again, see version).  In either case, 7-bit ASCII is the default character code (e.g., the clas-
       sification of which characters are printable) and sorting, and changing the LANG or LC_CTYPE environment  vari-
       ables causes a check for possible changes in these respects.

       When  using the system's NLS, the setlocale(3) function is called to determine appropriate character code/clas-
       sification and sorting (e.g., a 'en_CA.UTF-8' would yield "UTF-8" as a character code).   This  function  typi-
       cally  examines  the  LANG  and  LC_CTYPE  environment variables; refer to the system documentation for further
       details.  When not using the system's NLS, the shell simulates it by assuming that the ISO 8859-1 character set
       is used whenever either of the LANG and LC_CTYPE variables are set, regardless of their values.  Sorting is not
       affected for the simulated NLS.

       In addition, with both real and simulated NLS, all printable characters in the  range  \200-\377,  i.e.,  those
       that have M-char bindings, are automatically rebound to self-insert-command.  The corresponding binding for the
       escape-char sequence, if any, is left alone.  These characters are not  rebound  if  the  NOREBIND  environment
       variable  is  set.   This  may  be  useful for the simulated NLS or a primitive real NLS which assumes full ISO
       8859-1.  Otherwise, all M-char bindings in the range \240-\377 are effectively  undone.   Explicitly  rebinding
       the relevant keys with bindkey is of course still possible.

       Unknown  characters  (i.e.,  those that are neither printable nor control characters) are printed in the format
       \nnn.  If the tty is not in 8 bit mode, other 8 bit characters are printed by  converting  them  to  ASCII  and
       using  standout mode.  The shell never changes the 7/8 bit mode of the tty and tracks user-initiated changes of
       7/8 bit mode.  NLS users (or, for that matter, those who want to use a meta key) may need to explicitly set the
       tty in 8 bit mode through the appropriate stty(1) command in, e.g., the ~/.login file.

   OS variant support (+)
       A  number  of  new  builtin commands are provided to support features in particular operating systems.  All are
       described in detail in the Builtin commands section.

       On systems that support TCF (aix-ibm370, aix-ps2), getspath and setspath get and set the system execution path,
       getxvers and setxvers get and set the experimental version prefix and migrate migrates processes between sites.
       The jobs builtin prints the site on which each job is executing.

       Under BS2000, bs2cmd executes commands of the underlying BS2000/OSD operating system.

       Under Domain/OS, inlib adds shared libraries to the current environment, rootnode changes the rootnode and  ver
       changes the systype.

       Under Mach, setpath is equivalent to Mach's setpath(1).

       Under Masscomp/RTU and Harris CX/UX, universe sets the universe.

       Under Harris CX/UX, ucb or att runs a command under the specified universe.

       Under Convex/OS, warp prints or sets the universe.

       The  VENDOR,  OSTYPE  and MACHTYPE environment variables indicate respectively the vendor, operating system and
       machine type (microprocessor class or machine model) of the system on which the shell  thinks  it  is  running.
       These are particularly useful when sharing one's home directory between several types of machines; one can, for
       example,

           set path = (~/bin.$MACHTYPE /usr/ucb /bin /usr/bin .)

       in one's ~/.login and put executables compiled for each machine in the appropriate directory.

       The version shell variable indicates what options were chosen when the shell was compiled.

       Note also the newgrp builtin, the afsuser and echo_style shell variables and the system-dependent locations  of
       the shell's input files (see FILES).

   Signal handling
       Login  shells ignore interrupts when reading the file ~/.logout.  The shell ignores quit signals unless started
       with -q.  Login shells catch the terminate signal, but non-login shells inherit  the  terminate  behavior  from
       their parents.  Other signals have the values which the shell inherited from its parent.

       In  shell  scripts,  the shell's handling of interrupt and terminate signals can be controlled with onintr, and
       its handling of hangups can be controlled with hup and nohup.

       The shell exits on a hangup (see also the logout shell variable).  By default, the shell's children do too, but
       the  shell  does  not send them a hangup when it exits.  hup arranges for the shell to send a hangup to a child
       when it exits, and nohup sets a child to ignore hangups.

   Terminal management (+)
       The shell uses three different sets of terminal (''tty'') modes: 'edit', used when editing, 'quote', used  when
       quoting literal characters, and 'execute', used when executing commands.  The shell holds some settings in each
       mode constant, so commands which leave the tty in a confused state do not interfere with the shell.  The  shell
       also  matches changes in the speed and padding of the tty.  The list of tty modes that are kept constant can be
       examined and modified with the setty builtin.  Note that although the editor uses CBREAK mode (or  its  equiva-
       lent), it takes typed-ahead characters anyway.

       The  echotc,  settc and telltc commands can be used to manipulate and debug terminal capabilities from the com-
       mand line.

       On systems that support SIGWINCH or SIGWINDOW, the shell adapts to window resizing  automatically  and  adjusts
       the  environment  variables LINES and COLUMNS if set.  If the environment variable TERMCAP contains li# and co#
       fields, the shell adjusts them to reflect the new window size.

REFERENCE
       The next sections of this manual describe all of the available Builtin commands, Special  aliases  and  Special
       shell variables.

   Builtin commands
       %job    A synonym for the fg builtin command.

       %job &  A synonym for the bg builtin command.

       :       Does nothing, successfully.

       @
       @ name = expr
       @ name[index] = expr
       @ name++|--
       @ name[index]++|--
               The first form prints the values of all shell variables.

               The  second  form  assigns  the value of expr to name.  The third form assigns the value of expr to the
               index'th component of name; both name and its index'th component must already exist.

               expr may contain the operators '*', '+', etc., as in C.  If expr contains '<', '>', '&' or ''  then  at
               least  that  part  of  expr must be placed within '()'.  Note that the syntax of expr has nothing to do
               with that described under Expressions.

               The fourth and fifth forms increment ('++') or decrement ('--') name or its index'th component.

               The space between '@' and name is required.  The spaces between name and '=' and between '='  and  expr
               are optional.  Components of expr must be separated by spaces.

       alias [name [wordlist]]
               Without  arguments, prints all aliases.  With name, prints the alias for name.  With name and wordlist,
               assigns wordlist as the alias of name.  wordlist is command and filename substituted.  name may not  be
               'alias' or 'unalias'.  See also the unalias builtin command.

       alloc   Shows  the  amount of dynamic memory acquired, broken down into used and free memory.  With an argument
               shows the number of free and used blocks in each size category.  The categories start  at  size  8  and
               double  at  each  step.  This command's output may vary across system types, because systems other than
               the VAX may use a different memory allocator.

       bg [%job ...]
               Puts the specified jobs (or, without arguments, the current job) into the background,  continuing  each
               if it is stopped.  job may be a number, a string, '', '%', '+' or '-' as described under Jobs.

       bindkey [-l|-d|-e|-v|-u] (+)
       bindkey [-a] [-b] [-k] [-r] [--] key (+)
       bindkey [-a] [-b] [-k] [-c|-s] [--] key command (+)
               Without options, the first form lists all bound keys and the editor command to which each is bound, the
               second form lists the editor command to which key is bound and the third form binds the editor  command
               command to key.  Options include:

               -l  Lists all editor commands and a short description of each.
               -d  Binds all keys to the standard bindings for the default editor.
               -e  Binds all keys to the standard GNU Emacs-like bindings.
               -v  Binds all keys to the standard vi(1)-like bindings.
               -a  Lists  or  changes key-bindings in the alternative key map.  This is the key map used in vi command
                   mode.
               -b  key is interpreted as a control character written ^character (e.g., '^A') or C-character (e.g., 'C-
                   A'), a meta character written M-character (e.g., 'M-A'), a function key written F-string (e.g., 'F-
                   string'), or an extended prefix key written X-character (e.g., 'X-A').
               -k  key is interpreted as a symbolic arrow key name, which may  be  one  of  'down',  'up',  'left'  or
                   'right'.
               -r  Removes  key's  binding.  Be careful: 'bindkey -r' does not bind key to self-insert-command (q.v.),
                   it unbinds key completely.
               -c  command is interpreted as a builtin or external command instead of an editor command.
               -s  command is taken as a literal string and treated as terminal input when key is typed.   Bound  keys
                   in command are themselves reinterpreted, and this continues for ten levels of interpretation.
               --  Forces a break from option processing, so the next word is taken as key even if it begins with '-'.
               -u (or any invalid option)
                   Prints a usage message.

               key may be a single character or a string.  If a command is bound to a string, the first  character  of
               the string is bound to sequence-lead-in and the entire string is bound to the command.

               Control  characters  in key can be literal (they can be typed by preceding them with the editor command
               quoted-insert, normally bound to '^V') or written caret-character style, e.g., '^A'.  Delete is written
               '^?'  (caret-question mark).  key and command can contain backslashed escape sequences (in the style of
               System V echo(1)) as follows:

                   \a      Bell
                   \b      Backspace
                   \e      Escape
                   \f      Form feed
                   \n      Newline
                   \r      Carriage return
                   \t      Horizontal tab
                   \v      Vertical tab
                   \nnn    The ASCII character corresponding to the octal number nnn

               '\' nullifies the special meaning of the following character, if it has any, notably '\' and '^'.

       bs2cmd bs2000-command (+)
               Passes bs2000-command to the BS2000 command interpreter for execution.  Only  non-interactive  commands
               can be executed, and it is not possible to execute any command that would overlay the image of the cur-
               rent process, like /EXECUTE or /CALL-PROCEDURE. (BS2000 only)

       break   Causes execution to resume after the end of the nearest enclosing foreach or while.  The remaining com-
               mands  on  the  current line are executed.  Multi-level breaks are thus possible by writing them all on
               one line.

       breaksw Causes a break from a switch, resuming after the endsw.

       builtins (+)
               Prints the names of all builtin commands.

       bye (+) A synonym for the logout builtin command.  Available only if the shell was so compiled; see the version
               shell variable.

       case label:
               A label in a switch statement as discussed below.

       cd [-p] [-l] [-n|-v] [name]
               If  a directory name is given, changes the shell's working directory to name.  If not, changes to home.
               If name is '-' it is interpreted as the previous working directory (see Other substitutions).   (+)  If
               name  is not a subdirectory of the current directory (and does not begin with '/', './' or '../'), each
               component of the variable cdpath is checked to see if it has a subdirectory name.  Finally, if all else
               fails  but  name  is a shell variable whose value begins with '/', then this is tried to see if it is a
               directory.

               With -p, prints the final directory stack, just like dirs.  The -l, -n  and  -v  flags  have  the  same
               effect on cd as on dirs, and they imply -p.  (+)

               See also the implicitcd shell variable.

       chdir   A synonym for the cd builtin command.

       complete [command [word/pattern/list[:select]/[[suffix]/] ...]] (+)
               Without  arguments,  lists all completions.  With command, lists completions for command.  With command
               and word etc., defines completions.

               command may be a full command name or a glob-pattern (see Filename substitution).  It  can  begin  with
               '-' to indicate that completion should be used only when command is ambiguous.

               word  specifies  which word relative to the current word is to be completed, and may be one of the fol-
               lowing:

                   c   Current-word completion.  pattern is a glob-pattern which must match the beginning of the  cur-
                       rent word on the command line.  pattern is ignored when completing the current word.
                   C   Like c, but includes pattern when completing the current word.
                   n   Next-word completion.  pattern is a glob-pattern which must match the beginning of the previous
                       word on the command line.
                   N   Like n, but must match the beginning of the word two before the current word.
                   p   Position-dependent completion.  pattern is a numeric range, with the same syntax used to  index
                       shell variables, which must include the current word.

               list, the list of possible completions, may be one of the following:

                   a       Aliases
                   b       Bindings (editor commands)
                   c       Commands (builtin or external commands)
                   C       External commands which begin with the supplied path prefix
                   d       Directories
                   D       Directories which begin with the supplied path prefix
                   e       Environment variables
                   f       Filenames
                   F       Filenames which begin with the supplied path prefix
                   g       Groupnames
                   j       Jobs
                   l       Limits
                   n       Nothing
                   s       Shell variables
                   S       Signals
                   t       Plain (''text'') files
                   T       Plain (''text'') files which begin with the supplied path prefix
                   v       Any variables
                   u       Usernames
                   x       Like n, but prints select when list-choices is used.
                   X       Completions
                   $var    Words from the variable var
                   (...)   Words from the given list
                   '...'   Words from the output of command

               select  is  an  optional glob-pattern.  If given, words from only list that match select are considered
               and the fignore shell variable is ignored.  The last three types of completion may not  have  a  select
               pattern, and x uses select as an explanatory message when the list-choices editor command is used.

               suffix  is  a  single  character  to  be appended to a successful completion.  If null, no character is
               appended.  If omitted (in which case the fourth delimiter can also be omitted), a slash is appended  to
               directories and a space to other words.

               command  invoked  from  '...'  version  has  additional  environment variable set, the variable name is
               COMMAND_LINE and contains (as its name indicates) contents of the current (already  typed  in)  command
               line.  One can examine and use contents of the COMMAND_LINE variable in her custom script to build more
               sophisticated completions (see completion for svn(1) included in this package).

               Now for some examples.  Some commands take only directories as arguments, so there's no point  complet-
               ing plain files.

                   > complete cd 'p/1/d/'

               completes  only  the first word following 'cd' ('p/1') with a directory.  p-type completion can also be
               used to narrow down command completion:

                   > co[^D]
                   complete compress
                   > complete -co* 'p/0/(compress)/'
                   > co[^D]
                   > compress

               This completion completes commands (words in position 0, 'p/0') which begin with  'co'  (thus  matching
               'co*') to 'compress' (the only word in the list).  The leading '-' indicates that this completion is to
               be used with only ambiguous commands.

                   > complete find 'n/-user/u/'

               is an example of n-type completion.  Any word following 'find' and  immediately  following  '-user'  is
               completed from the list of users.

                   > complete cc 'c/-I/d/'

               demonstrates  c-type  completion.   Any  word  following 'cc' and beginning with '-I' is completed as a
               directory.  '-I' is not taken as part of the directory because we used lowercase c.

               Different lists are useful with different commands.

                   > complete alias 'p/1/a/'
                   > complete man 'p/*/c/'
                   > complete set 'p/1/s/'
                   > complete true 'p/1/x:Truth has no options./'

               These complete words following 'alias' with aliases, 'man' with commands, and 'set'  with  shell  vari-
               ables.   'true'  doesn't  have  any  options, so x does nothing when completion is attempted and prints
               'Truth has no options.' when completion choices are listed.

               Note that the man example, and several other examples below, could just as  well  have  used  'c/*'  or
               'n/*' as 'p/*'.

               Words can be completed from a variable evaluated at completion time,

                   > complete ftp 'p/1/$hostnames/'
                   > set hostnames = (rtfm.mit.edu tesla.ee.cornell.edu)
                   > ftp [^D]
                   rtfm.mit.edu tesla.ee.cornell.edu
                   > ftp [^C]
                   > set hostnames = (rtfm.mit.edu tesla.ee.cornell.edu uunet.uu.net)
                   > ftp [^D]
                   rtfm.mit.edu tesla.ee.cornell.edu uunet.uu.net

               or from a command run at completion time:

                   > complete kill 'p/*/'ps | awk \{print\ \$1\}'/'
                   > kill -9 [^D]
                   23113 23377 23380 23406 23429 23529 23530 PID

               Note  that  the  complete  command does not itself quote its arguments, so the braces, space and '$' in
               '{print $1}' must be quoted explicitly.

               One command can have multiple completions:

                   > complete dbx 'p/2/(core)/' 'p/*/c/'

               completes the second argument to 'dbx' with the word 'core' and  all  other  arguments  with  commands.
               Note  that the positional completion is specified before the next-word completion.  Because completions
               are evaluated from left to right, if the next-word completion were  specified  first  it  would  always
               match  and the positional completion would never be executed.  This is a common mistake when defining a
               completion.

               The select pattern is useful when a command takes files with only particular forms as  arguments.   For
               example,

                   > complete cc 'p/*/f:*.[cao]/'

               completes  'cc'  arguments to files ending in only '.c', '.a', or '.o'.  select can also exclude files,
               using negation of a glob-pattern as described under Filename substitution.  One might use

                   > complete rm 'p/*/f:^*.{c,h,cc,C,tex,1,man,l,y}/'

               to exclude precious source code from 'rm' completion.  Of course, one could still type  excluded  names
               manually  or  override  the completion mechanism using the complete-word-raw or list-choices-raw editor
               commands (q.v.).

               The 'C', 'D', 'F' and 'T' lists are like 'c', 'd', 'f' and 't' respectively, but they  use  the  select
               argument  in  a different way: to restrict completion to files beginning with a particular path prefix.
               For example, the Elm mail program uses '=' as an abbreviation for one's mail directory.  One might use

                   > complete elm c@=@F:$HOME/Mail/@

               to complete 'elm -f =' as if it were 'elm -f ~/Mail/'.  Note that we used '@' instead of '/'  to  avoid
               confusion with the select argument, and we used '$HOME' instead of '~' because home directory substitu-
               tion works at only the beginning of a word.

               suffix is used to add a nonstandard suffix (not space or '/' for directories) to completed words.

                   > complete finger 'c/*@/$hostnames/' 'p/1/u/@'

               completes arguments to 'finger' from the list of users, appends an '@', and then  completes  after  the
               '@' from the 'hostnames' variable.  Note again the order in which the completions are specified.

               Finally, here's a complex example for inspiration:

                   > complete find \
                   'n/-name/f/' 'n/-newer/f/' 'n/-{,n}cpio/f/' \
                   ?n/-exec/c/' 'n/-ok/c/' 'n/-user/u/' \
                   'n/-group/g/' 'n/-fstype/(nfs 4.2)/' \
                   'n/-type/(b c d f l p s)/' \
                   ?c/-/(name newer cpio ncpio exec ok user \
                   group fstype type atime ctime depth inum \
                   ls mtime nogroup nouser perm print prune \
                   size xdev)/' \
                   'p/*/d/'

               This  completes  words  following '-name', '-newer', '-cpio' or 'ncpio' (note the pattern which matches
               both) to files, words following '-exec' or '-ok' to commands, words following  'user'  and  'group'  to
               users  and  groups respectively and words following '-fstype' or '-type' to members of the given lists.
               It also completes the switches themselves from the given list (note the use of c-type  completion)  and
               completes anything not otherwise completed to a directory.  Whew.

               Remember  that  programmed  completions are ignored if the word being completed is a tilde substitution
               (beginning with '~') or a variable (beginning with '$').  complete is an experimental feature, and  the
               syntax may change in future versions of the shell.  See also the uncomplete builtin command.

       continue
               Continues execution of the nearest enclosing while or foreach.  The rest of the commands on the current
               line are executed.

       default:
               Labels the default case in a switch statement.  It should come after all case labels.

       dirs [-l] [-n|-v]
       dirs -S|-L [filename] (+)
       dirs -c (+)
               The first form prints the directory stack.  The top of the stack is at the left and the first directory
               in the stack is the current directory.  With -l, '~' or '~name' in the output is expanded explicitly to
               home or the pathname of the home directory for user name.  (+) With -n, entries are wrapped before they
               reach  the  edge of the screen.  (+) With -v, entries are printed one per line, preceded by their stack
               positions.  (+) If more than one of -n or -v is given, -v takes precedence.  -p is  accepted  but  does
               nothing.

               With  -S,  the  second form saves the directory stack to filename as a series of cd and pushd commands.
               With -L, the shell sources filename, which is presumably a directory stack file saved by the -S  option
               or the savedirs mechanism.  In either case, dirsfile is used if filename is not given and ~/.cshdirs is
               used if dirsfile is unset.

               Note that login shells do the equivalent of 'dirs -L' on startup and, if savedirs  is  set,  'dirs  -S'
               before  exiting.   Because only ~/.tcshrc is normally sourced before ~/.cshdirs, dirsfile should be set
               in ~/.tcshrc rather than ~/.login.

               The last form clears the directory stack.

       echo [-n] word ...
               Writes each word to the shell's standard output, separated by spaces and  terminated  with  a  newline.
               The  echo_style shell variable may be set to emulate (or not) the flags and escape sequences of the BSD
               and/or System V versions of echo; see echo(1).

       echotc [-sv] arg ... (+)
               Exercises the terminal capabilities (see termcap(5)) in args.  For example,  'echotc  home'  sends  the
               cursor  to  the home position, 'echotc cm 3 10' sends it to column 3 and row 10, and 'echotc ts 0; echo
               "This is a test."; echotc fs' prints "This is a test."  in the status line.

               If arg is 'baud', 'cols', 'lines', 'meta' or 'tabs', prints the value of that capability ("yes" or "no"
               indicating  that  the  terminal does or does not have that capability).  One might use this to make the
               output from a shell script less verbose on slow terminals, or limit command output  to  the  number  of
               lines on the screen:

                   > set history='echotc lines'
                   > @ history--

               Termcap strings may contain wildcards which will not echo correctly.  One should use double quotes when
               setting a shell variable to a terminal capability string, as in the following example that  places  the
               date in the status line:

                   > set tosl="'echotc ts 0'"
                   > set frsl="'echotc fs'"
                   > echo -n "$tosl";date; echo -n "$frsl"

               With  -s, nonexistent capabilities return the empty string rather than causing an error.  With -v, mes-
               sages are verbose.

       else
       end
       endif
       endsw   See the description of the foreach, if, switch, and while statements below.

       eval arg ...
               Treats the arguments as input to the shell and executes the resulting command(s) in the context of  the
               current shell.  This is usually used to execute commands generated as the result of command or variable
               substitution, because parsing occurs before these substitutions.  See tset(1) for a sample use of eval.

       exec command
               Executes the specified command in place of the current shell.

       exit [expr]
               The  shell exits either with the value of the specified expr (an expression, as described under Expres-
               sions) or, without expr, with the value 0.

       fg [%job ...]
               Brings the specified jobs (or, without arguments, the current job) into the foreground, continuing each
               if  it  is  stopped.   job may be a number, a string, '', '%', '+' or '-' as described under Jobs.  See
               also the run-fg-editor editor command.

       filetest -op file ... (+)
               Applies op (which is a file inquiry operator as described under File inquiry operators)  to  each  file
               and returns the results as a space-separated list.

       foreach name (wordlist)
       ...
       end     Successively  sets  the  variable name to each member of wordlist and executes the sequence of commands
               between this command and the matching end.  (Both foreach and end must appear alone on separate lines.)
               The builtin command continue may be used to continue the loop prematurely and the builtin command break
               to terminate it prematurely.  When this command is read from  the  terminal,  the  loop  is  read  once
               prompting  with 'foreach? ' (or prompt2) before any statements in the loop are executed.  If you make a
               mistake typing in a loop at the terminal you can rub it out.

       getspath (+)
               Prints the system execution path.  (TCF only)

       getxvers (+)
               Prints the experimental version prefix.  (TCF only)

       glob wordlist
               Like echo, but the '-n' parameter is not recognized and words are delimited by null characters  in  the
               output.  Useful for programs which wish to use the shell to filename expand a list of words.

       goto word
               word  is filename and command-substituted to yield a string of the form 'label'.  The shell rewinds its
               input as much as possible, searches for a line of the form 'label:', possibly  preceded  by  blanks  or
               tabs, and continues execution after that line.

       hashstat
               Prints a statistics line indicating how effective the internal hash table has been at locating commands
               (and avoiding exec's).  An exec is attempted for each component of the path  where  the  hash  function
               indicates a possible hit, and in each component which does not begin with a '/'.

               On machines without vfork(2), prints only the number and size of hash buckets.

       history [-hTr] [n]
       history -S|-L|-M [filename] (+)
       history -c (+)
               The  first form prints the history event list.  If n is given only the n most recent events are printed
               or saved.  With -h, the history list is printed without leading numbers.  If -T  is  specified,  times-
               tamps  are  printed also in comment form.  (This can be used to produce files suitable for loading with
               'history -L' or 'source -h'.)  With -r, the order of printing is most recent first rather  than  oldest
               first.

               With  -S,  the second form saves the history list to filename.  If the first word of the savehist shell
               variable is set to a number, at most that many lines are saved.  If the second word of savehist is  set
               to 'merge', the history list is merged with the existing history file instead of replacing it (if there
               is one) and sorted by time stamp.  (+) Merging is intended for an environment like the X Window  System
               with  several  shells  in simultaneous use.  Currently it succeeds only when the shells quit nicely one
               after another.

               With -L, the shell appends filename, which is presumably a history list saved by the -S option  or  the
               savehist  mechanism,  to the history list.  -M is like -L, but the contents of filename are merged into
               the history list and sorted by timestamp.  In either case, histfile is used if filename  is  not  given
               and  ~/.history  is used if histfile is unset.  'history -L' is exactly like 'source -h' except that it
               does not require a filename.

               Note that login shells do the equivalent of 'history -L' on startup and, if savehist is  set,  'history
               -S'  before  exiting.  Because only ~/.tcshrc is normally sourced before ~/.history, histfile should be
               set in ~/.tcshrc rather than ~/.login.

               If histlit is set, the first and second forms print and save the literal (unexpanded) form of the  his-
               tory list.

               The last form clears the history list.

       hup [command] (+)
               With command, runs command such that it will exit on a hangup signal and arranges for the shell to send
               it a hangup signal when the shell exits.  Note that commands may set their  own  response  to  hangups,
               overriding  hup.   Without  an argument (allowed in only a shell script), causes the shell to exit on a
               hangup for the remainder of the script.  See also Signal handling and the nohup builtin command.

       if (expr) command
               If expr (an expression, as described under Expressions)  evaluates  true,  then  command  is  executed.
               Variable  substitution  on  command happens early, at the same time it does for the rest of the if com-
               mand.  command must be a simple command, not an alias, a pipeline, a command list  or  a  parenthesized
               command  list,  but  it  may have arguments.  Input/output redirection occurs even if expr is false and
               command is thus not executed; this is a bug.

       if (expr) then
       ...
       else if (expr2) then
       ...
       else
       ...
       endif   If the specified expr is true then the commands to the first else are executed; otherwise if  expr2  is
               true then the commands to the second else are executed, etc.  Any number of else-if pairs are possible;
               only one endif is needed.  The else part is likewise optional.  (The words else and endif  must  appear
               at the beginning of input lines; the if must appear alone on its input line or after an else.)

       inlib shared-library ... (+)
               Adds  each  shared-library  to  the  current  environment.  There is no way to remove a shared library.
               (Domain/OS only)

       jobs [-l]
               Lists the active jobs.  With -l, lists process IDs in addition to the normal information.  On TCF  sys-
               tems, prints the site on which each job is executing.

       kill [-s signal] %job|pid ...
       kill -l The  first and second forms sends the specified signal (or, if none is given, the TERM (terminate) sig-
               nal) to the specified jobs or processes.  job may be a number,  a  string,  '',  '%',  '+'  or  '-'  as
               described  under  Jobs.   Signals  are either given by number or by name (as given in /usr/include/sig-
               nal.h, stripped of the prefix 'SIG').  There is no default job; saying just 'kill' does not send a sig-
               nal  to the current job.  If the signal being sent is TERM (terminate) or HUP (hangup), then the job or
               process is sent a CONT (continue) signal as well.  The third form lists the signal names.

       limit [-h] [resource [maximum-use]]
               Limits the consumption by the current process and each process it creates to  not  individually  exceed
               maximum-use  on the specified resource.  If no maximum-use is given, then the current limit is printed;
               if no resource is given, then all limitations are given.  If the -h flag is given, the hard limits  are
               used instead of the current limits.  The hard limits impose a ceiling on the values of the current lim-
               its.  Only the super-user may raise the hard limits, but a user may lower or raise the  current  limits
               within the legal range.

               Controllable resources currently include (if supported by the OS):

               cputime
                      the maximum number of cpu-seconds to be used by each process

               filesize
                      the largest single file which can be created

               datasize
                      the maximum growth of the data+stack region via sbrk(2) beyond the end of the program text

               stacksize
                      the maximum size of the automatically-extended stack region

               coredumpsize
                      the size of the largest core dump that will be created

               memoryuse
                      the  maximum  amount of physical memory a process may have allocated to it at a given time (this
                      is not implemented in the 2.6 kernel. The value is meaningless and changing this value will have
                      no effect)

               heapsize
                      the maximum amount of memory a process may allocate per brk() system call

               descriptors or openfiles
                      the maximum number of open files for this process

               concurrency
                      the maximum number of threads for this process

               memorylocked
                      the maximum size which a process may lock into memory using mlock(2)

               maxproc
                      the maximum number of simultaneous processes for this user id

               sbsize the maximum size of socket buffer usage for this user

               swapsize
                      the maximum amount of swap space reserved or used for this user

               maximum-use  may  be given as a (floating point or integer) number followed by a scale factor.  For all
               limits other than cputime the default scale is 'k' or 'kilobytes' (1024 bytes); a scale factor  of  'm'
               or  'megabytes'  may also be used.  For cputime the default scaling is 'seconds', while 'm' for minutes
               or 'h' for hours, or a time of the form 'mm:ss' giving minutes and seconds may be used.

               For both resource names and scale factors, unambiguous prefixes of the names suffice.

       log (+) Prints the watch shell variable and reports on each user indicated in watch who is logged  in,  regard-
               less of when they last logged in.  See also watchlog.

       login   Terminates  a  login  shell,  replacing  it with an instance of /bin/login. This is one way to log off,
               included for compatibility with sh(1).

       logout  Terminates a login shell.  Especially useful if ignoreeof is set.

       ls-F [-switch ...] [file ...] (+)
               Lists files like 'ls -F', but much faster.  It identifies each type of special file in the listing with
               a special character:

               /   Directory
               *   Executable
               #   Block device
               %   Character device
               |   Named pipe (systems with named pipes only)
               =   Socket (systems with sockets only)
               @   Symbolic link (systems with symbolic links only)
               +   Hidden directory (AIX only) or context dependent (HP/UX only)
               :   Network special (HP/UX only)

               If  the  listlinks shell variable is set, symbolic links are identified in more detail (on only systems
               that have them, of course):

               @   Symbolic link to a non-directory
               >   Symbolic link to a directory
               &   Symbolic link to nowhere

               listlinks also slows down ls-F and causes partitions holding files pointed to by symbolic links  to  be
               mounted.

               If  the  listflags  shell  variable is set to 'x', 'a' or 'A', or any combination thereof (e.g., 'xA'),
               they are used as flags to ls-F, making it act like 'ls -xF', 'ls -Fa', 'ls -FA' or a combination (e.g.,
               'ls  -FxA').   On  machines where 'ls -C' is not the default, ls-F acts like 'ls -CF', unless listflags
               contains an 'x', in which case it acts like 'ls -xF'.  ls-F passes its arguments  to  ls(1)  if  it  is
               given any switches, so 'alias ls ls-F' generally does the right thing.

               The ls-F builtin can list files using different colors depending on the filetype or extension.  See the
               color tcsh variable and the LS_COLORS environment variable.

       migrate [-site] pid|%jobid ... (+)
       migrate -site (+)
               The first form migrates the process or job to the site specified or the default site determined by  the
               system  path.   The second form is equivalent to 'migrate -site $$': it migrates the current process to
               the specified site.  Migrating the shell itself can cause unexpected behavior, because the  shell  does
               not like to lose its tty.  (TCF only)

       newgrp [-] group (+)
               Equivalent  to 'exec newgrp'; see newgrp(1).  Available only if the shell was so compiled; see the ver-
               sion shell variable.

       nice [+number] [command]
               Sets the scheduling priority for the shell to number, or, without number, to  4.   With  command,  runs
               command  at  the  appropriate  priority.   The  greater the number, the less cpu the process gets.  The
               super-user may specify negative priority by using 'nice -number ...'.  Command is always executed in  a
               sub-shell, and the restrictions placed on commands in simple if statements apply.

       nohup [command]
               With  command,  runs command such that it will ignore hangup signals.  Note that commands may set their
               own response to hangups, overriding nohup.  Without an argument  (allowed  in  only  a  shell  script),
               causes  the  shell to ignore hangups for the remainder of the script.  See also Signal handling and the
               hup builtin command.

       notify [%job ...]
               Causes the shell to notify the user asynchronously when the status of any of the  specified  jobs  (or,
               without  %job, the current job) changes, instead of waiting until the next prompt as is usual.  job may
               be a number, a string, '', '%', '+' or '-' as described under Jobs.  See also the  notify  shell  vari-
               able.

       onintr [-|label]
               Controls  the action of the shell on interrupts.  Without arguments, restores the default action of the
               shell on interrupts, which is to terminate shell scripts or to return to  the  terminal  command  input
               level.  With '-', causes all interrupts to be ignored.  With label, causes the shell to execute a 'goto
               label' when an interrupt is received or a child process terminates because it was interrupted.

               onintr is ignored if the shell is running detached and in  system  startup  files  (see  FILES),  where
               interrupts are disabled anyway.

       popd [-p] [-l] [-n|-v] [+n]
               Without  arguments, pops the directory stack and returns to the new top directory.  With a number '+n',
               discards the n'th entry in the stack.

               Finally, all forms of popd print the final directory stack, just  like  dirs.   The  pushdsilent  shell
               variable  can  be set to prevent this and the -p flag can be given to override pushdsilent.  The -l, -n
               and -v flags have the same effect on popd as on dirs.  (+)

       printenv [name] (+)
               Prints the names and values of all environment variables or, with name, the value  of  the  environment
               variable name.

       pushd [-p] [-l] [-n|-v] [name|+n]
               Without arguments, exchanges the top two elements of the directory stack.  If pushdtohome is set, pushd
               without arguments does 'pushd ~', like cd.  (+) With name, pushes the current  working  directory  onto
               the  directory  stack  and  changes  to name.  If name is '-' it is interpreted as the previous working
               directory (see Filename substitution).  (+) If dunique is set, pushd removes any instances of name from
               the  stack  before  pushing  it onto the stack.  (+) With a number '+n', rotates the nth element of the
               directory stack around to be the top element and changes to it.  If dextract is  set,  however,  'pushd
               +n' extracts the nth directory, pushes it onto the top of the stack and changes to it.  (+)

               Finally,  all  forms  of  pushd print the final directory stack, just like dirs.  The pushdsilent shell
               variable can be set to prevent this and the -p flag can be given to override pushdsilent.  The  -l,  -n
               and -v flags have the same effect on pushd as on dirs.  (+)

       rehash  Causes  the  internal  hash  table of the contents of the directories in the path variable to be recom-
               puted.  This is needed if new commands are added to directories in path while you are logged in.   This
               should be necessary only if you add commands to one of your own directories, or if a systems programmer
               changes the contents of one of the system directories.  Also flushes  the  cache  of  home  directories
               built by tilde expansion.

       repeat count command
               The  specified  command,  which  is  subject to the same restrictions as the command in the one line if
               statement above, is executed count times.  I/O redirections occur exactly once, even if count is 0.

       rootnode //nodename (+)
               Changes the rootnode to //nodename, so that '/' will be interpreted as '//nodename'.  (Domain/OS only)

       sched (+)
       sched [+]hh:mm command (+)
       sched -n (+)
               The first form prints the scheduled-event list.  The sched shell variable may be set to define the for-
               mat  in which the scheduled-event list is printed.  The second form adds command to the scheduled-event
               list.  For example,

                   > sched 11:00 echo It\'s eleven o\'clock.

               causes the shell to echo 'It's eleven o'clock.' at 11 AM.  The time may be in 12-hour AM/PM format

                   > sched 5pm set prompt='[%h] It\'s after 5; go home: >'

               or may be relative to the current time:

                   > sched +2:15 /usr/lib/uucp/uucico -r1 -sother

               A relative time specification may not use AM/PM format.  The third form removes item n from  the  event
               list:

                   > sched
                        1  Wed Apr  4 15:42  /usr/lib/uucp/uucico -r1 -sother
                        2  Wed Apr  4 17:00  set prompt=[%h] It's after 5; go home: >
                   > sched -2
                   > sched
                        1  Wed Apr  4 15:42  /usr/lib/uucp/uucico -r1 -sother

               A  command  in  the  scheduled-event list is executed just before the first prompt is printed after the
               time when the command is scheduled.  It is possible to miss the exact time when the command  is  to  be
               run, but an overdue command will execute at the next prompt.  A command which comes due while the shell
               is waiting for user input is executed immediately.  However, normal  operation  of  an  already-running
               command will not be interrupted so that a scheduled-event list element may be run.

               This  mechanism  is similar to, but not the same as, the at(1) command on some Unix systems.  Its major
               disadvantage is that it may not run a command at exactly the specified time.  Its  major  advantage  is
               that because sched runs directly from the shell, it has access to shell variables and other structures.
               This provides a mechanism for changing one's working environment based on the time of day.

       set
       set name ...
       set name=word ...
       set [-r] [-f|-l] name=(wordlist) ... (+)
       set name[index]=word ...
       set -r (+)
       set -r name ... (+)
       set -r name=word ... (+)
               The first form of the command prints the value of all shell variables.  Variables  which  contain  more
               than  a  single word print as a parenthesized word list.  The second form sets name to the null string.
               The third form sets name to the single word.  The fourth form  sets  name  to  the  list  of  words  in
               wordlist.   In  all cases the value is command and filename expanded.  If -r is specified, the value is
               set read-only.  If -f or -l are specified, set only unique words keeping their order.  -f  prefers  the
               first  occurrence  of  a  word, and -l the last.  The fifth form sets the index'th component of name to
               word; this component must already exist.  The sixth form lists only the names of  all  shell  variables
               that  are read-only.  The seventh form makes name read-only, whether or not it has a value.  The eighth
               form is the same as the third form, but make name read-only at the same time.

               These arguments can be repeated to set and/or make read-only multiple variables in a  single  set  com-
               mand.   Note,  however,  that  variable  expansion happens for all arguments before any setting occurs.
               Note also that '=' can be adjacent to both name and word or separated from both by whitespace, but can-
               not be adjacent to only one or the other.  See also the unset builtin command.

       setenv [name [value]]
               Without  arguments,  prints  the  names  and values of all environment variables.  Given name, sets the
               environment variable name to value or, without value, to the null string.

       setpath path (+)
               Equivalent to setpath(1).  (Mach only)

       setspath LOCAL|site|cpu ... (+)
               Sets the system execution path.  (TCF only)

       settc cap value (+)
               Tells the shell to believe that the terminal capability cap (as defined in termcap(5))  has  the  value
               value.   No  sanity  checking  is done.  Concept terminal users may have to 'settc xn no' to get proper
               wrapping at the rightmost column.

       setty [-d|-q|-x] [-a] [[+|-]mode] (+)
               Controls which tty modes (see Terminal management) the shell does not allow to change.  -d,  -q  or  -x
               tells setty to act on the 'edit', 'quote' or 'execute' set of tty modes respectively; without -d, -q or
               -x, 'execute' is used.

               Without other arguments, setty lists the modes in the chosen set which are fixed on  ('+mode')  or  off
               ('-mode').   The available modes, and thus the display, vary from system to system.  With -a, lists all
               tty modes in the chosen set whether or not they are fixed.  With +mode, -mode or mode, fixes mode on or
               off  or  removes  control from mode in the chosen set.  For example, 'setty +echok echoe' fixes 'echok'
               mode on and allows commands to turn 'echoe' mode on or off, both when the shell is executing  commands.

       setxvers [string] (+)
               Set the experimental version prefix to string, or removes it if string is omitted.  (TCF only)

       shift [variable]
               Without  arguments,  discards  argv[1]  and shifts the members of argv to the left.  It is an error for
               argv not to be set or to have less than one word as value.  With variable, performs the  same  function
               on variable.

       source [-h] name [args ...]
               The  shell reads and executes commands from name.  The commands are not placed on the history list.  If
               any args are given, they are placed in argv.  (+) source commands may be nested; if they are nested too
               deeply  the  shell  may  run out of file descriptors.  An error in a source at any level terminates all
               nested source commands.  With -h, commands are placed on the history list instead  of  being  executed,
               much like 'history -L'.

       stop %job|pid ...
               Stops  the  specified  jobs or processes which are executing in the background.  job may be a number, a
               string, '', '%', '+' or '-' as described under Jobs.  There is no default job; saying just 'stop'  does
               not stop the current job.

       suspend Causes  the  shell  to  stop in its tracks, much as if it had been sent a stop signal with ^Z.  This is
               most often used to stop shells started by su(1).

       switch (string)
       case str1:
           ...
           breaksw
       ...
       default:
           ...
           breaksw
       endsw   Each case label is successively matched, against the specified string which is first command and  file-
               name expanded.  The file metacharacters '*', '?' and '[...]'  may be used in the case labels, which are
               variable expanded.  If none of the labels match before a 'default' label is found, then  the  execution
               begins  after the default label.  Each case label and the default label must appear at the beginning of
               a line.  The command breaksw causes execution to continue after the endsw.  Otherwise control may  fall
               through case labels and default labels as in C.  If no label matches and there is no default, execution
               continues after the endsw.

       telltc (+)
               Lists the values of all terminal capabilities (see termcap(5)).

       termname [terminal type] (+)
               Tests if terminal type (or the current value of TERM if no terminal type is given) has an entry in  the
               hosts  termcap(5) or terminfo(5) database. Prints the terminal type to stdout and returns 0 if an entry
               is present otherwise returns 1.

       time [command]
               Executes command (which must be a simple command, not an alias, a pipeline, a command list or a  paren-
               thesized  command  list) and prints a time summary as described under the time variable.  If necessary,
               an extra shell is created to print the time statistic when the  command  completes.   Without  command,
               prints a time summary for the current shell and its children.

       umask [value]
               Sets  the  file  creation  mask to value, which is given in octal.  Common values for the mask are 002,
               giving all access to the group and read and execute access to others, and 022, giving read and  execute
               access to the group and others.  Without value, prints the current file creation mask.

       unalias pattern
               Removes  all  aliases  whose  names match pattern.  'unalias *' thus removes all aliases.  It is not an
               error for nothing to be unaliased.

       uncomplete pattern (+)
               Removes all completions whose names match pattern.  'uncomplete *' thus removes all completions.  It is
               not an error for nothing to be uncompleted.

       unhash  Disables use of the internal hash table to speed location of executed programs.

       universe universe (+)
               Sets the universe to universe.  (Masscomp/RTU only)

       unlimit [-hf] [resource]
               Removes the limitation on resource or, if no resource is specified, all resource limitations.  With -h,
               the corresponding hard limits are removed.  Only the super-user may do this.  Note that unlimit may not
               exit  successful,  since  most  systems  do  not allow descriptors to be unlimited.  With -f errors are
               ignored.

       unset pattern
               Removes all variables whose names match pattern, unless they are read-only.  'unset *' thus removes all
               variables unless they are read-only; this is a bad idea.  It is not an error for nothing to be unset.

       unsetenv pattern
               Removes all environment variables whose names match pattern.  'unsetenv *' thus removes all environment
               variables; this is a bad idea.  It is not an error for nothing to be unsetenved.

       ver [systype [command]] (+)
               Without arguments, prints SYSTYPE.  With systype, sets SYSTYPE to systype.  With systype  and  command,
               executes command under systype.  systype may be 'bsd4.3' or 'sys5.3'.  (Domain/OS only)

       wait    The  shell  waits  for all background jobs.  If the shell is interactive, an interrupt will disrupt the
               wait and cause the shell to print the names and job numbers of all outstanding jobs.

       warp universe (+)
               Sets the universe to universe.  (Convex/OS only)

       watchlog (+)
               An alternate name for the log builtin command (q.v.).  Available only if the shell was so compiled; see
               the version shell variable.

       where command (+)
               Reports all known instances of command, including aliases, builtins and executables in path.

       which command (+)
               Displays  the command that will be executed by the shell after substitutions, path searching, etc.  The
               builtin command is just like which(1), but it correctly reports tcsh aliases and builtins and is 10  to
               100 times faster.  See also the which-command editor command.

       while (expr)
       ...
       end     Executes  the  commands  between the while and the matching end while expr (an expression, as described
               under Expressions) evaluates non-zero.  while and end must appear alone on their  input  lines.   break
               and  continue  may  be used to terminate or continue the loop prematurely.  If the input is a terminal,
               the user is prompted the first time through the loop as with foreach.

   Special aliases (+)
       If set, each of these aliases executes automatically at the indicated time.  They are all initially  undefined.

       beepcmd Runs when the shell wants to ring the terminal bell.

       cwdcmd  Runs  after every change of working directory.  For example, if the user is working on an X window sys-
               tem using xterm(1) and a re-parenting window manager that supports title bars such as twm(1) and does

                   > alias cwdcmd  'echo -n "^[]2;${HOST}:$cwd ^G"'

               then the shell will change the title of the running xterm(1) to be the name of the host, a  colon,  and
               the full current working directory.  A fancier way to do that is

                   > alias cwdcmd 'echo -n "^[]2;${HOST}:$cwd^G^[]1;${HOST}^G"'

               This  will  put  the  hostname and working directory on the title bar but only the hostname in the icon
               manager menu.

               Note that putting a cd, pushd or popd in cwdcmd may cause an infinite loop.  It is the author's opinion
               that anyone doing so will get what they deserve.

       jobcmd  Runs before each command gets executed, or when the command changes state.  This is similar to postcmd,
               but it does not print builtins.

                   > alias jobcmd  'echo -n "^[]2\;\!#:q^G"'

               then executing vi foo.c will put the command string in the xterm title bar.

       helpcommand
               Invoked by the run-help editor command.  The command name for which help is sought is  passed  as  sole
               argument.  For example, if one does

                   > alias helpcommand '\!:1 --help'

               then  the  help  display  of the command itself will be invoked, using the GNU help calling convention.
               Currently there is no easy way to account for various calling conventions  (e.g.,  the  customary  Unix
               '-h'), except by using a table of many commands.

       periodic
               Runs  every  tperiod  minutes.   This provides a convenient means for checking on common but infrequent
               changes such as new mail.  For example, if one does

                   > set tperiod = 30
                   > alias periodic checknews

               then the checknews(1) program runs every 30 minutes.  If periodic is set but tperiod is unset or set to
               0, periodic behaves like precmd.

       precmd  Runs just before each prompt is printed.  For example, if one does

                   > alias precmd date

               then  date(1)  runs just before the shell prompts for each command.  There are no limits on what precmd
               can be set to do, but discretion should be used.

       postcmd Runs before each command gets executed.

                   > alias postcmd  'echo -n "^[]2\;\!#:q^G"'

               then executing vi foo.c will put the command string in the xterm title bar.

       shell   Specifies the interpreter for executable scripts which do not themselves specify an  interpreter.   The
               first   word   should   be   a  full  path  name  to  the  desired  interpreter  (e.g.,  '/bin/csh'  or
               '/usr/local/bin/tcsh').

   Special shell variables
       The variables described in this section have special meaning to the shell.

       The shell sets addsuffix, argv, autologout, csubstnonl, command, echo_style, edit, gid, group,  home,  loginsh,
       oid,  path,  prompt, prompt2, prompt3, shell, shlvl, tcsh, term, tty, uid, user and version at startup; they do
       not change thereafter unless changed by the user.  The shell updates cwd, dirstack, owd and status when  neces-
       sary, and sets logout on logout.

       The  shell  synchronizes  group,  home,  path,  shlvl, term and user with the environment variables of the same
       names: whenever the environment variable changes the shell changes the corresponding shell  variable  to  match
       (unless  the  shell  variable  is  read-only)  and  vice  versa.  Note that although cwd and PWD have identical
       meanings, they are not synchronized in this manner, and that the shell automatically interconverts the  differ-
       ent formats of path and PATH.

       addsuffix (+)
               If  set,  filename completion adds '/' to the end of directories and a space to the end of normal files
               when they are matched exactly.  Set by default.

       afsuser (+)
               If set, autologout's autolock feature uses its value instead of the local username for kerberos authen-
               tication.

       ampm (+)
               If set, all times are shown in 12-hour AM/PM format.

       anyerror (+)
               This  variable selects what is propagated to the value of the status variable. For more information see
               the description of the status variable below.

       argv    The arguments to the shell.  Positional parameters are taken from  argv,  i.e.,  '$1'  is  replaced  by
               '$argv[1]', etc.  Set by default, but usually empty in interactive shells.

       autocorrect (+)
               If set, the spell-word editor command is invoked automatically before each completion attempt.

       autoexpand (+)
               If  set,  the expand-history editor command is invoked automatically before each completion attempt. If
               this is set to onlyhistory, then only history will be expanded and  a  second  completion  will  expand
               filenames.

       autolist (+)
               If  set,  possibilities are listed after an ambiguous completion.  If set to 'ambiguous', possibilities
               are listed only when no new characters are added by completion.

       autologout (+)
               The first word is the number of minutes of inactivity before automatic  logout.   The  optional  second
               word  is  the  number  of minutes of inactivity before automatic locking.  When the shell automatically
               logs out, it prints 'auto-logout', sets the variable logout to 'automatic' and exits.  When  the  shell
               automatically  locks,  the  user is required to enter his password to continue working.  Five incorrect
               attempts result in automatic logout.  Set to '60' (automatic logout after 60 minutes, and  no  locking)
               by default in login and superuser shells, but not if the shell thinks it is running under a window sys-
               tem (i.e., the DISPLAY environment variable is set), the tty is a pseudo-tty (pty) or the shell was not
               so compiled (see the version shell variable).  See also the afsuser and logout shell variables.

       backslash_quote (+)
               If  set, backslashes ('\') always quote '\', ''', and '"'.  This may make complex quoting tasks easier,
               but it can cause syntax errors in csh(1) scripts.

       catalog The file name of the message catalog.  If set, tcsh use 'tcsh.${catalog}' as a message catalog  instead
               of default 'tcsh'.

       cdpath  A  list of directories in which cd should search for subdirectories if they aren't found in the current
               directory.

       color   If set, it enables color display for the builtin ls-F and it passes --color=auto to ls.  Alternatively,
               it  can  be  set to only ls-F or only ls to enable color to only one command.  Setting it to nothing is
               equivalent to setting it to (ls-F ls).

       colorcat
               If set, it enables color escape sequence for NLS message files.  And display colorful NLS messages.

       command (+)
               If set, the command which was passed to the shell with the -c flag (q.v.).

       compat_expr (+)
               If set, the shell will evaluate expressions right to left, like the original csh.

       complete (+)
               If set to 'enhance', completion 1) ignores case and 2) considers periods, hyphens and underscores ('.',
               '-'  and  '_') to be word separators and hyphens and underscores to be equivalent. If set to 'igncase',
               the completion becomes case insensitive.

       continue (+)
               If set to a list of commands, the shell will continue the listed commands, instead of  starting  a  new
               one.

       continue_args (+)
               Same as continue, but the shell will execute:

                   echo 'pwd' $argv > ~/.<cmd>_pause; %<cmd>

       correct (+)
               If  set  to  'cmd',  commands are automatically spelling-corrected.  If set to 'complete', commands are
               automatically completed.  If set to 'all', the entire command line is corrected.

       csubstnonl (+)
               If set, newlines and carriage returns in command substitution are replaced by spaces.  Set by  default.

       cwd     The full pathname of the current directory.  See also the dirstack and owd shell variables.

       dextract (+)
               If  set,  'pushd +n' extracts the nth directory from the directory stack rather than rotating it to the
               top.

       dirsfile (+)
               The default location in which 'dirs -S' and 'dirs -L' look for a history file.  If unset, ~/.cshdirs is
               used.   Because  only  ~/.tcshrc  is  normally  sourced  before  ~/.cshdirs,  dirsfile should be set in
               ~/.tcshrc rather than ~/.login.

       dirstack (+)
               An array of all the directories on the directory stack.  '$dirstack[1]' is the current  working  direc-
               tory, '$dirstack[2]' the first directory on the stack, etc.  Note that the current working directory is
               '$dirstack[1]' but '=0' in directory stack substitutions, etc.  One can change the stack arbitrarily by
               setting  dirstack,  but  the first element (the current working directory) is always correct.  See also
               the cwd and owd shell variables.

       dspmbyte (+)
               Has an affect iff 'dspm' is listed as part of the version shell variable.  If set to 'euc', it  enables
               display  and editing EUC-kanji(Japanese) code.  If set to 'sjis', it enables display and editing Shift-
               JIS(Japanese) code.  If set to 'big5', it enables display and editing Big5(Chinese) code.   If  set  to
               'utf8',  it enables display and editing Utf8(Unicode) code.  If set to the following format, it enables
               display and editing of original multi-byte code format:

                   > set dspmbyte = 0000....(256 bytes)....0000

               The table requires just 256 bytes.  Each character of 256 characters corresponds (from left  to  right)
               to the ASCII codes 0x00, 0x01, ... 0xff.  Each character is set to number 0,1,2 and 3.  Each number has
               the following meaning:
                 0 ... not used for multi-byte characters.
                 1 ... used for the first byte of a multi-byte character.
                 2 ... used for the second byte of a multi-byte character.
                 3 ... used for both the first byte and second byte of a multi-byte character.







                 Example:
               If set to '001322', the first character (means 0x00 of the ASCII code) and second character (means 0x01
               of  ASCII  code)  are  set  to '0'.  Then, it is not used for multi-byte characters.  The 3rd character
               (0x02) is set to '1', indicating that it is used for the first byte of a multi-byte character.  The 4th
               character(0x03)  is  set  '3'.   It is used for both the first byte and the second byte of a multi-byte
               character.  The 5th and 6th characters (0x04,0x05) are set to '2', indicating that they  are  used  for
               the second byte of a multi-byte character.

               The  GNU  fileutils  version  of  ls  cannot  display multi-byte filenames without the -N ( --literal )
               option.   If you are using this version, set the second word of dspmbyte to "ls".  If not, for example,
               "ls-F -l" cannot display multi-byte filenames.

                 Note:
               This variable can only be used if KANJI and DSPMBYTE has been defined at compile time.

       dunique (+)
               If set, pushd removes any instances of name from the stack before pushing it onto the stack.

       echo    If set, each command with its arguments is echoed just before it is executed.  For non-builtin commands
               all expansions occur before echoing.  Builtin commands are echoed before command and filename substitu-
               tion, because these substitutions are then done selectively.  Set by the -x command line option.

       echo_style (+)
               The style of the echo builtin.  May be set to

               bsd     Don't echo a newline if the first argument is '-n'.
               sysv    Recognize backslashed escape sequences in echo strings.
               both    Recognize both the '-n' flag and backslashed escape sequences; the default.
               none    Recognize neither.

               Set  by default to the local system default.  The BSD and System V options are described in the echo(1)
               man pages on the appropriate systems.

       edit (+)
               If set, the command-line editor is used.  Set by default in interactive shells.

       ellipsis (+)
               If set, the '%c'/'%.' and '%C' prompt sequences (see the prompt shell variable) indicate skipped direc-
               tories with an ellipsis ('...')  instead of '/<skipped>'.

       fignore (+)
               Lists file name suffixes to be ignored by completion.

       filec   In  tcsh, completion is always used and this variable is ignored by default. If edit is unset, then the
               traditional csh completion is used.  If set in csh, filename completion is used.

       gid (+) The user's real group ID.

       group (+)
               The user's group name.

       highlight
               If set, the incremental search match (in i-search-back and i-search-fwd) and  the  region  between  the
               mark and the cursor are highlighted in reverse video.

               Highlighting requires more frequent terminal writes, which introduces extra overhead. If you care about
               terminal performance, you may want to leave this unset.

       histchars
               A string value determining the characters used in History substitution (q.v.).  The first character  of
               its value is used as the history substitution character, replacing the default character '!'.  The sec-
               ond character of its value replaces the character '^' in quick substitutions.

       histdup (+)
               Controls handling of duplicate entries in the history list.  If set to 'all' only unique history events
               are  entered  in the history list.  If set to 'prev' and the last history event is the same as the cur-
               rent command, then the current command is not entered in the history.  If set to 'erase' and  the  same
               event is found in the history list, that old event gets erased and the current one gets inserted.  Note
               that the 'prev' and 'all' options renumber history events so there are no gaps.

       histfile (+)
               The default location in which 'history -S' and 'history -L' look for a history file.  If unset, ~/.his-
               tory  is  used.  histfile is useful when sharing the same home directory between different machines, or
               when saving separate histories on different terminals.  Because  only  ~/.tcshrc  is  normally  sourced
               before ~/.history, histfile should be set in ~/.tcshrc rather than ~/.login.

       histlit (+)
               If  set,  builtin  and  editor commands and the savehist mechanism use the literal (unexpanded) form of
               lines in the history list.  See also the toggle-literal-history editor command.

       history The first word indicates the number of history events to save.  The optional second word (+)  indicates
               the format in which history is printed; if not given, '%h\t%T\t%R\n' is used.  The format sequences are
               described below under prompt; note the variable meaning of '%R'.  Set to '100' by default.

       home    Initialized to the home directory of the invoker.  The filename expansion of '~' refers to  this  vari-
               able.

       ignoreeof
               If  set to the empty string or '0' and the input device is a terminal, the end-of-file command (usually
               generated by the user by typing '^D' on an empty line) causes the shell to print 'Use "exit"  to  leave
               tcsh.'  instead of exiting.  This prevents the shell from accidentally being killed.  Historically this
               setting exited after 26 successive EOF's to avoid infinite loops.  If set to  a  number  n,  the  shell
               ignores  n  -  1  consecutive  end-of-files and exits on the nth.  (+) If unset, '1' is used, i.e., the
               shell exits on a single '^D'.

       implicitcd (+)
               If set, the shell treats a directory name typed as a command as though it were a request to  change  to
               that  directory.   If  set  to verbose, the change of directory is echoed to the standard output.  This
               behavior is inhibited in non-interactive shell scripts, or for command strings with more than one word.
               Changing  directory  takes  precedence  over executing a like-named command, but it is done after alias
               substitutions.  Tilde and variable expansions work as expected.

       inputmode (+)
               If set to 'insert' or 'overwrite', puts the editor into that input mode at the beginning of each  line.

       killdup (+)
               Controls  handling  of  duplicate  entries  in  the kill ring.  If set to 'all' only unique strings are
               entered in the kill ring.  If set to 'prev' and the last killed string  is  the  same  as  the  current
               killed  string,  then  the  current  string is not entered in the ring.  If set to 'erase' and the same
               string is found in the kill ring, the old string is erased and the current one is inserted.

       killring (+)
               Indicates the number of killed strings to keep in memory.  Set to '30' by default.  If unset or set  to
               less  than '2', the shell will only keep the most recently killed string.  Strings are put in the kill-
               ring by the editor commands that delete (kill) strings of text, e.g.  backward-delete-word,  kill-line,
               etc,  as  well as the copy-region-as-kill command.  The yank editor command will yank the most recently
               killed string into the command-line, while yank-pop (see Editor commands) can be used to  yank  earlier
               killed strings.

       listflags (+)
               If  set  to  'x',  'a' or 'A', or any combination thereof (e.g., 'xA'), they are used as flags to ls-F,
               making it act like 'ls -xF', 'ls -Fa', 'ls -FA' or a combination (e.g., 'ls -FxA'): 'a' shows all files
               (even  if they start with a '.'), 'A' shows all files but '.' and '..', and 'x' sorts across instead of
               down.  If the second word of listflags is set, it is used as the path to 'ls(1)'.

       listjobs (+)
               If set, all jobs are listed when a job is suspended.  If set to 'long', the listing is in long  format.

       listlinks (+)
               If set, the ls-F builtin command shows the type of file to which each symbolic link points.

       listmax (+)
               The maximum number of items which the list-choices editor command will list without asking first.

       listmaxrows (+)
               The  maximum  number  of  rows  of items which the list-choices editor command will list without asking
               first.

       loginsh (+)
               Set by the shell if it is a login shell.  Setting or unsetting it within a shell has  no  effect.   See
               also shlvl.

       logout (+)
               Set  by  the  shell  to  'normal'  before  a normal logout, 'automatic' before an automatic logout, and
               'hangup' if the shell was killed by a hangup signal (see Signal handling).   See  also  the  autologout
               shell variable.

       mail    The  names of the files or directories to check for incoming mail, separated by whitespace, and option-
               ally preceded by a numeric word.  Before each prompt, if 10 minutes have passed since the  last  check,
               the  shell  checks  each  file and says 'You have new mail.' (or, if mail contains multiple files, 'You
               have new mail in name.') if the filesize is greater than zero in  size  and  has  a  modification  time
               greater than its access time.


               If  you  are in a login shell, then no mail file is reported unless it has been modified after the time
               the shell has started up, to prevent redundant  notifications.   Most  login  programs  will  tell  you
               whether or not you have mail when you log in.

               If  a  file specified in mail is a directory, the shell will count each file within that directory as a
               separate message, and will report 'You have n mails.' or 'You have n mails in  name.'  as  appropriate.
               This functionality is provided primarily for those systems which store mail in this manner, such as the
               Andrew Mail System.

               If the first word of mail is numeric it is taken as a different mail checking interval, in seconds.

               Under very rare circumstances, the shell may report 'You have mail.' instead of 'You have new mail.'

       matchbeep (+)
               If set to 'never', completion never beeps.  If set to 'nomatch', it beeps only when there is no  match.
               If  set to 'ambiguous', it beeps when there are multiple matches.  If set to 'notunique', it beeps when
               there is one exact and other longer matches.  If unset, 'ambiguous' is used.

       nobeep (+)
               If set, beeping is completely disabled.  See also visiblebell.

       noclobber
               If set, restrictions are placed on output  redirection  to  insure  that  files  are  not  accidentally
               destroyed and that '>>' redirections refer to existing files, as described in the Input/output section.

       noding  If set, disable the printing of 'DING!' in the prompt time specifiers at the change of hour.

       noglob  If set, Filename substitution and Directory stack substitution (q.v.) are inhibited.  This is most use-
               ful  in  shell scripts which do not deal with filenames, or after a list of filenames has been obtained
               and further expansions are not desirable.

       nokanji (+)
               If set and the shell supports Kanji (see the version shell variable), it is disabled so that  the  meta
               key can be used.

       nonomatch
               If  set, a Filename substitution or Directory stack substitution (q.v.) which does not match any exist-
               ing files is left untouched rather than causing an error.  It is still an error for the substitution to
               be malformed, e.g., 'echo [' still gives an error.

       nostat (+)
               A list of directories (or glob-patterns which match directories; see Filename substitution) that should
               not be stat(2)ed during a completion operation.  This is usually used to exclude directories which take
               too much time to stat(2), for example /afs.

       notify  If  set, the shell announces job completions asynchronously.  The default is to present job completions
               just before printing a prompt.

       oid (+) The user's real organization ID.  (Domain/OS only)

       owd (+) The old working directory, equivalent to the '-' used by cd and pushd.  See also the cwd  and  dirstack
               shell variables.

       padhour If  set,  enable  the printing of padding '0' for hours, in 24 and 12 hour formats.  E.G.: 07:45:42 vs.
               7:45:42

       path    A list of directories in which to look for executable commands.  A  null  word  specifies  the  current
               directory.   If  there  is no path variable then only full path names will execute.  path is set by the
               shell at startup from the PATH environment variable or, if PATH does not exist, to  a  system-dependent
               default  something  like  '(/usr/local/bin  /usr/bsd /bin /usr/bin .)'.  The shell may put '.' first or
               last in path or omit it entirely depending on how it was compiled; see the version shell  variable.   A
               shell  which  is  given neither the -c nor the -t option hashes the contents of the directories in path
               after reading ~/.tcshrc and each time path is reset.  If one adds a new command to a directory in  path
               while the shell is active, one may need to do a rehash for the shell to find it.

       printexitvalue (+)
               If set and an interactive program exits with a non-zero status, the shell prints 'Exit status'.

       prompt  The  string  which is printed before reading each command from the terminal.  prompt may include any of
               the following formatting sequences (+), which are replaced by the given information:

               %/  The current working directory.
               %~  The current working directory, but with one's home directory represented by '~'  and  other  users'
                   home directories represented by '~user' as per Filename substitution.  '~user' substitution happens
                   only if the shell has already used '~user' in a pathname in the current session.
               %c[[0]n], %.[[0]n]
                   The trailing component of the current working directory, or n trailing components if a digit  n  is
                   given.  If n begins with '0', the number of skipped components precede the trailing component(s) in
                   the format '/<skipped>trailing'.  If the ellipsis shell variable is  set,  skipped  components  are
                   represented by an ellipsis so the whole becomes '...trailing'.  '~' substitution is done as in '%~'
                   above, but the '~' component is ignored when counting trailing components.
               %C  Like %c, but without '~' substitution.
               %h, %!, !
                   The current history event number.
               %M  The full hostname.
               %m  The hostname up to the first '.'.
               %S (%s)
                   Start (stop) standout mode.
               %B (%b)
                   Start (stop) boldfacing mode.
               %U (%u)
                   Start (stop) underline mode.
               %t, %@
                   The time of day in 12-hour AM/PM format.
               %T  Like '%t', but in 24-hour format (but see the ampm shell variable).
               %p  The 'precise' time of day in 12-hour AM/PM format, with seconds.
               %P  Like '%p', but in 24-hour format (but see the ampm shell variable).
               \c  c is parsed as in bindkey.
               ^c  c is parsed as in bindkey.
               %%  A single '%'.
               %n  The user name.
               %j  The number of jobs.
               %d  The weekday in 'Day' format.
               %D  The day in 'dd' format.
               %w  The month in 'Mon' format.
               %W  The month in 'mm' format.
               %y  The year in 'yy' format.
               %Y  The year in 'yyyy' format.
               %l  The shell's tty.
               %L  Clears from the end of the prompt to end of the display or the end of the line.
               %$  Expands the shell or environment variable name immediately after the '$'.
               %#  '>' (or the first character of the promptchars shell variable) for normal users, '#' (or the second
                   character of promptchars) for the superuser.
               %{string%}
                   Includes string as a literal escape sequence.  It should be used only to change terminal attributes
                   and should not move the cursor location.  This cannot be the last sequence in prompt.
               %?  The return code of the command executed just before the prompt.
               %R  In prompt2, the status of the parser.  In prompt3, the corrected string.  In history,  the  history
                   string.

               '%B',  '%S',  '%U' and '%{string%}' are available in only eight-bit-clean shells; see the version shell
               variable.

               The bold, standout and underline sequences are often used to distinguish a superuser shell.  For  exam-
               ple,

                   > set prompt = "%m [%h] %B[%@]%b [%/] you rang? "
                   tut [37] [2:54pm] [/usr/accts/sys] you rang? _

               If  '%t', '%@', '%T', '%p', or '%P' is used, and noding is not set, then print 'DING!' on the change of
               hour (i.e, ':00' minutes) instead of the actual time.

               Set by default to '%# ' in interactive shells.

       prompt2 (+)
               The string with which to prompt in while and foreach loops and after lines ending  in  '\'.   The  same
               format sequences may be used as in prompt (q.v.); note the variable meaning of '%R'.  Set by default to
               '%R? ' in interactive shells.

       prompt3 (+)
               The string with which to prompt  when  confirming  automatic  spelling  correction.   The  same  format
               sequences  may be used as in prompt (q.v.); note the variable meaning of '%R'.  Set by default to 'COR-
               RECT>%R (y|n|e|a)? ' in interactive shells.

       promptchars (+)
               If set (to a two-character string), the '%#' formatting  sequence  in  the  prompt  shell  variable  is
               replaced with the first character for normal users and the second character for the superuser.

       pushdtohome (+)
               If set, pushd without arguments does 'pushd ~', like cd.

       pushdsilent (+)
               If set, pushd and popd do not print the directory stack.

       recexact (+)
               If set, completion completes on an exact match even if a longer match is possible.

       recognize_only_executables (+)
               If set, command listing displays only files in the path that are executable.  Slow.

       rmstar (+)
               If set, the user is prompted before 'rm *' is executed.

       rprompt (+)
               The  string  to print on the right-hand side of the screen (after the command input) when the prompt is
               being displayed on the left.  It recognizes the same formatting characters as prompt.  It will automat-
               ically  disappear  and  reappear  as  necessary,  to ensure that command input isn't obscured, and will
               appear only if the prompt, command input, and itself will fit together on  the  first  line.   If  edit
               isn't set, then rprompt will be printed after the prompt and before the command input.

       savedirs (+)
               If  set,  the  shell does 'dirs -S' before exiting.  If the first word is set to a number, at most that
               many directory stack entries are saved.

       savehist
               If set, the shell does 'history -S' before exiting.  If the first word is set to a number, at most that
               many  lines  are saved.  (The number must be less than or equal to history.)  If the second word is set
               to 'merge', the history list is merged with the existing history file instead of replacing it (if there
               is one) and sorted by time stamp and the most recent events are retained.  (+)

       sched (+)
               The  format in which the sched builtin command prints scheduled events; if not given, '%h\t%T\t%R\n' is
               used.  The format sequences are described above under prompt; note the variable meaning of '%R'.

       shell   The file in which the shell resides.  This is used in forking shells to interpret files which have exe-
               cute  bits  set,  but which are not executable by the system.  (See the description of Builtin and non-
               builtin command execution.)  Initialized to the (system-dependent) home of the shell.

       shlvl (+)
               The number of nested shells.  Reset to 1 in login shells.  See also loginsh.

       status  The exit status from the last command or backquote expansion, or any command in a  pipeline  is  propa-
               gated to status.  (This is also the default csh behavior.)  This default does not match what POSIX man-
               dates (to return the status of the last command only). To match the POSIX behavior, you need  to  unset
               anyerror.

               If  the anyerror variable is unset, the exit status of a pipeline is determined only from the last com-
               mand in the pipeline, and the exit status of a backquote expansion is not propagated to status.

               If a command terminated abnormally, then 0200 is added to the  status.   Builtin  commands  which  fail
               return exit status '1', all other builtin commands return status '0'.

       symlinks (+)
               Can be set to several different values to control symbolic link ('symlink') resolution:

               If set to 'chase', whenever the current directory changes to a directory containing a symbolic link, it
               is expanded to the real name of the directory to which the link points.  This does  not  work  for  the
               user's home directory; this is a bug.

               If  set to 'ignore', the shell tries to construct a current directory relative to the current directory
               before the link was crossed.  This means that cding through a symbolic link and then 'cd ..'ing returns
               one to the original directory.  This affects only builtin commands and filename completion.

               If  set  to  'expand', the shell tries to fix symbolic links by actually expanding arguments which look
               like path names.  This affects any command, not just builtins.  Unfortunately, this does not  work  for
               hard-to-recognize  filenames, such as those embedded in command options.  Expansion may be prevented by
               quoting.  While this setting is usually the most convenient, it is sometimes misleading  and  sometimes
               confusing  when  it  fails  to  recognize an argument which should be expanded.  A compromise is to use
               'ignore' and use the editor command normalize-path (bound by default to ^X-n) when necessary.

               Some examples are in order.  First, let's set up some play directories:

                   > cd /tmp
                   > mkdir from from/src to
                   > ln -s from/src to/dst

               Here's the behavior with symlinks unset,

                   > cd /tmp/to/dst; echo $cwd
                   /tmp/to/dst
                   > cd ..; echo $cwd
                   /tmp/from

               here's the behavior with symlinks set to 'chase',

                   > cd /tmp/to/dst; echo $cwd
                   /tmp/from/src
                   > cd ..; echo $cwd
                   /tmp/from

               here's the behavior with symlinks set to 'ignore',

                   > cd /tmp/to/dst; echo $cwd
                   /tmp/to/dst
                   > cd ..; echo $cwd
                   /tmp/to

               and here's the behavior with symlinks set to 'expand'.

                   > cd /tmp/to/dst; echo $cwd
                   /tmp/to/dst
                   > cd ..; echo $cwd
                   /tmp/to
                   > cd /tmp/to/dst; echo $cwd
                   /tmp/to/dst
                   > cd ".."; echo $cwd
                   /tmp/from
                   > /bin/echo ..
                   /tmp/to
                   > /bin/echo ".."
                   ..

               Note that 'expand' expansion 1) works just like 'ignore' for builtins like cd, 2) is prevented by quot-
               ing, and 3) happens before filenames are passed to non-builtin commands.

       tcsh (+)
               The  version  number  of the shell in the format 'R.VV.PP', where 'R' is the major release number, 'VV'
               the current version and 'PP' the patchlevel.

       term    The terminal type.  Usually set in ~/.login as described under Startup and shutdown.

       time    If set to a number, then the time builtin (q.v.) executes automatically after each command which  takes
               more than that many CPU seconds.  If there is a second word, it is used as a format string for the out-
               put of the time builtin.  (u) The following sequences may be used in the format string:

               %U  The time the process spent in user mode in cpu seconds.
               %S  The time the process spent in kernel mode in cpu seconds.
               %E  The elapsed (wall clock) time in seconds.
               %P  The CPU percentage computed as (%U + %S) / %E.
               %W  Number of times the process was swapped.
               %X  The average amount in (shared) text space used in Kbytes.
               %D  The average amount in (unshared) data/stack space used in Kbytes.
               %K  The total space used (%X + %D) in Kbytes.
               %M  The maximum memory the process had in use at any time in Kbytes.
               %F  The number of major page faults (page needed to be brought from disk).
               %R  The number of minor page faults.
               %I  The number of input operations.
               %O  The number of output operations.
               %r  The number of socket messages received.
               %s  The number of socket messages sent.
               %k  The number of signals received.
               %w  The number of voluntary context switches (waits).
               %c  The number of involuntary context switches.

               Only the first four sequences are supported on systems  without  BSD  resource  limit  functions.   The
               default  time format is '%Uu %Ss %E %P %X+%Dk %I+%Oio %Fpf+%Ww' for systems that support resource usage
               reporting and '%Uu %Ss %E %P' for systems that do not.

               Under Sequent's DYNIX/ptx, %X, %D, %K, %r and %s  are  not  available,  but  the  following  additional
               sequences are:

               %Y  The number of system calls performed.
               %Z  The number of pages which are zero-filled on demand.
               %i  The number of times a process's resident set size was increased by the kernel.
               %d  The number of times a process's resident set size was decreased by the kernel.
               %l  The number of read system calls performed.
               %m  The number of write system calls performed.
               %p  The number of reads from raw disk devices.
               %q  The number of writes to raw disk devices.

               and  the  default time format is '%Uu %Ss %E %P %I+%Oio %Fpf+%Ww'.  Note that the CPU percentage can be
               higher than 100% on multi-processors.

       tperiod (+)
               The period, in minutes, between executions of the periodic special alias.

       tty (+) The name of the tty, or empty if not attached to one.

       uid (+) The user's real user ID.

       user    The user's login name.

       verbose If set, causes the words of each command to be printed, after history substitution (if  any).   Set  by
               the -v command line option.

       version (+)
               The version ID stamp.  It contains the shell's version number (see tcsh), origin, release date, vendor,
               operating system and machine (see VENDOR, OSTYPE and MACHTYPE) and a comma-separated  list  of  options
               which were set at compile time.  Options which are set by default in the distribution are noted.

               8b    The shell is eight bit clean; default
               7b    The shell is not eight bit clean
               wide  The shell is multibyte encoding clean (like UTF-8)
               nls   The system's NLS is used; default for systems with NLS
               lf    Login  shells  execute  /etc/csh.login before instead of after /etc/csh.cshrc and ~/.login before
                     instead of after ~/.tcshrc and ~/.history.
               dl    '.' is put last in path for security; default
               nd    '.' is omitted from path for security
               vi    vi-style editing is the default rather than emacs
               dtr   Login shells drop DTR when exiting
               bye   bye is a synonym for logout and log is an alternate name for watchlog
               al    autologout is enabled; default
               kan   Kanji is used if appropriate according to locale settings, unless the nokanji shell  variable  is
                     set
               sm    The system's malloc(3) is used
               hb    The '#!<program> <args>' convention is emulated when executing shell scripts
               ng    The newgrp builtin is available
               rh    The shell attempts to set the REMOTEHOST environment variable
               afs   The  shell  verifies  your  password with the kerberos server if local authentication fails.  The
                     afsuser shell variable or the AFSUSER environment variable override your local username if set.

               An administrator may enter additional strings to indicate differences in the local version.

       visiblebell (+)
               If set, a screen flash is used rather than the audible bell.  See also nobeep.

       watch (+)
               A list of user/terminal pairs to watch for logins and logouts.  If either the user is 'any' all  termi-
               nals are watched for the given user and vice versa.  Setting watch to '(any any)' watches all users and
               terminals.  For example,

                   set watch = (george ttyd1 any console $user any)

               reports activity of the user 'george' on ttyd1, any user on the console, and oneself (or a  trespasser)
               on any terminal.

               Logins and logouts are checked every 10 minutes by default, but the first word of watch can be set to a
               number to check every so many minutes.  For example,

                   set watch = (1 any any)

               reports any login/logout once every minute.  For the impatient, the  log  builtin  command  triggers  a
               watch  report  at  any  time.   All current logins are reported (as with the log builtin) when watch is
               first set.

               The who shell variable controls the format of watch reports.

       who (+) The format string for watch messages.  The following sequences are replaced by the given information:

               %n  The name of the user who logged in/out.
               %a  The observed action, i.e., 'logged on', 'logged off' or 'replaced olduser on'.
               %l  The terminal (tty) on which the user logged in/out.
               %M  The full hostname of the remote host, or 'local' if the login/logout was from the local host.
               %m  The hostname of the remote host up to the first '.'.  The full name is  printed  if  it  is  an  IP
                   address or an X Window System display.

               %M and %m are available on only systems that store the remote hostname in /etc/utmp.  If unset, '%n has
               %a %l from %m.' is used, or '%n has %a %l.' on systems which don't store the remote hostname.

       wordchars (+)
               A list of non-alphanumeric characters to be considered part of a word by  the  forward-word,  backward-
               word etc., editor commands.  If unset, '*?_-.[]~=' is used.

ENVIRONMENT
       AFSUSER (+)
               Equivalent to the afsuser shell variable.

       COLUMNS The number of columns in the terminal.  See Terminal management.

       DISPLAY Used by X Window System (see X(1)).  If set, the shell does not set autologout (q.v.).

       EDITOR  The  pathname to a default editor.  See also the VISUAL environment variable and the run-fg-editor edi-
               tor command.

       GROUP (+)
               Equivalent to the group shell variable.

       HOME    Equivalent to the home shell variable.

       HOST (+)
               Initialized to the name of the machine on which the shell is running, as  determined  by  the  gethost-
               name(2) system call.

       HOSTTYPE (+)
               Initialized  to the type of machine on which the shell is running, as determined at compile time.  This
               variable is obsolete and will be removed in a future version.

       HPATH (+)
               A colon-separated list of directories in which the run-help editor command looks for command documenta-
               tion.

       LANG    Gives the preferred character environment.  See Native Language System support.

       LC_CTYPE
               If set, only ctype character handling is changed.  See Native Language System support.

       LINES   The number of lines in the terminal.  See Terminal management.

       LS_COLORS
               The  format  of  this  variable is reminiscent of the termcap(5) file format; a colon-separated list of
               expressions of the form "xx=string", where "xx" is a two-character variable name.  The  variables  with
               their associated defaults are:

                   no   0      Normal (non-filename) text
                   fi   0      Regular file
                   di   01;34  Directory
                   ln   01;36  Symbolic link
                   pi   33     Named pipe (FIFO)
                   so   01;35  Socket
                   do   01;35  Door
                   bd   01;33  Block device
                   cd   01;32  Character device
                   ex   01;32  Executable file
                   mi   (none) Missing file (defaults to fi)
                   or   (none) Orphaned symbolic link (defaults to ln)
                   lc   ^[[    Left code
                   rc   m      Right code
                   ec   (none) End code (replaces lc+no+rc)

               You need to include only the variables you want to change from the default.

               File names can also be colorized based on filename extension.  This is specified in the LS_COLORS vari-
               able using the syntax "*ext=string".  For example, using ISO 6429 codes, to color all C-language source
               files blue you would specify "*.c=34".  This would color all files ending in .c in blue (34) color.

               Control  characters can be written either in C-style-escaped notation, or in stty-like ^-notation.  The
               C-style notation adds ^[ for Escape, _ for a normal space character, and ? for  Delete.   In  addition,
               the ^[ escape character can be used to override the default interpretation of ^[, ^, : and =.

               Each  file  will  be written as <lc> <color-code> <rc> <filename> <ec>.  If the <ec> code is undefined,
               the sequence <lc> <no> <rc> will be used instead.  This is generally more convenient to use,  but  less
               general.   The  left,  right and end codes are provided so you don't have to type common parts over and
               over again and to support weird terminals; you will generally not need to change  them  at  all  unless
               your terminal does not use ISO 6429 color sequences but a different system.

               If  your  terminal  does use ISO 6429 color codes, you can compose the type codes (i.e., all except the
               lc, rc, and ec codes) from numerical commands separated by semicolons.  The most common commands are:

                       0   to restore default color
                       1   for brighter colors
                       4   for underlined text
                       5   for flashing text
                       30  for black foreground
                       31  for red foreground
                       32  for green foreground
                       33  for yellow (or brown) foreground
                       34  for blue foreground
                       35  for purple foreground
                       36  for cyan foreground
                       37  for white (or gray) foreground
                       40  for black background
                       41  for red background
                       42  for green background
                       43  for yellow (or brown) background
                       44  for blue background
                       45  for purple background
                       46  for cyan background
                       47  for white (or gray) background

               Not all commands will work on all systems or display devices.

               A few terminal programs do not recognize the default end code properly.  If  all  text  gets  colorized
               after  you  do  a directory listing, try changing the no and fi codes from 0 to the numerical codes for
               your standard fore- and background colors.

       MACHTYPE (+)
               The machine type (microprocessor class or machine model), as determined at compile time.

       NOREBIND (+)
               If set, printable characters are not rebound to self-insert-command.  See Native Language  System  sup-
               port.

       OSTYPE (+)
               The operating system, as determined at compile time.

       PATH    A  colon-separated  list of directories in which to look for executables.  Equivalent to the path shell
               variable, but in a different format.

       PWD (+) Equivalent to the cwd shell variable, but not synchronized to it; updated only after an  actual  direc-
               tory change.

       REMOTEHOST (+)
               The  host  from  which  the  user  has logged in remotely, if this is the case and the shell is able to
               determine it.  Set only if the shell was so compiled; see the version shell variable.

       SHLVL (+)
               Equivalent to the shlvl shell variable.

       SYSTYPE (+)
               The current system type.  (Domain/OS only)

       TERM    Equivalent to the term shell variable.

       TERMCAP The terminal capability string.  See Terminal management.

       USER    Equivalent to the user shell variable.

       VENDOR (+)
               The vendor, as determined at compile time.

       VISUAL  The pathname to a default full-screen editor.  See also the EDITOR environment variable and the run-fg-
               editor editor command.

FILES
       /etc/csh.cshrc  Read  first  by  every  shell.   ConvexOS,  Stellix  and  Intel  use  /etc/cshrc  and NeXTs use
                       /etc/cshrc.std.  A/UX, AMIX, Cray and IRIX have no equivalent in csh(1), but read this file  in
                       tcsh anyway.  Solaris 2.x does not have it either, but tcsh reads /etc/.cshrc.  (+)
       /etc/csh.login  Read  by  login shells after /etc/csh.cshrc.  ConvexOS, Stellix and Intel use /etc/login, NeXTs
                       use /etc/login.std, Solaris 2.x uses /etc/.login and A/UX, AMIX, Cray and IRIX use  /etc/cshrc.
       ~/.tcshrc (+)   Read by every shell after /etc/csh.cshrc or its equivalent.
       ~/.cshrc        Read  by every shell, if ~/.tcshrc doesn't exist, after /etc/csh.cshrc or its equivalent.  This
                       manual uses '~/.tcshrc' to mean '~/.tcshrc or, if ~/.tcshrc is not found, ~/.cshrc'.
       ~/.history      Read by login shells after ~/.tcshrc if savehist is set, but see also histfile.
       ~/.login        Read by login shells after ~/.tcshrc or ~/.history.  The shell may be compiled to read ~/.login
                       before instead of after ~/.tcshrc and ~/.history; see the version shell variable.
       ~/.cshdirs (+)  Read by login shells after ~/.login if savedirs is set, but see also dirsfile.
       /etc/csh.logout Read  by  login  shells  at  logout.  ConvexOS, Stellix and Intel use /etc/logout and NeXTs use
                       /etc/logout.std.  A/UX, AMIX, Cray and IRIX have no equivalent in csh(1), but read this file in
                       tcsh anyway.  Solaris 2.x does not have it either, but tcsh reads /etc/.logout.  (+)
       ~/.logout       Read by login shells at logout after /etc/csh.logout or its equivalent.
       /bin/sh         Used to interpret shell scripts not starting with a '#'.
       /tmp/sh*        Temporary file for '<<'.
       /etc/passwd     Source of home directories for '~name' substitutions.

       The order in which startup files are read may differ if the shell was so compiled; see Startup and shutdown and
       the version shell variable.

NEW FEATURES (+)
       This manual describes tcsh as a single entity, but experienced csh(1) users will want to pay special  attention
       to tcsh's new features.

       A  command-line  editor, which supports GNU Emacs or vi(1)-style key bindings.  See The command-line editor and
       Editor commands.

       Programmable, interactive word completion and listing.  See Completion and listing and the complete and  uncom-
       plete builtin commands.

       Spelling correction (q.v.) of filenames, commands and variables.

       Editor commands (q.v.) which perform other useful functions in the middle of typed commands, including documen-
       tation lookup (run-help), quick editor restarting (run-fg-editor) and command resolution (which-command).

       An enhanced history mechanism.  Events in the history list are time-stamped.  See also the history command  and
       its associated shell variables, the previously undocumented '#' event specifier and new modifiers under History
       substitution, the *-history, history-search-*, i-search-*, vi-search-* and toggle-literal-history  editor  com-
       mands and the histlit shell variable.

       Enhanced  directory  parsing and directory stack handling.  See the cd, pushd, popd and dirs commands and their
       associated shell variables, the description of Directory stack substitution, the  dirstack,  owd  and  symlinks
       shell variables and the normalize-command and normalize-path editor commands.

       Negation in glob-patterns.  See Filename substitution.

       New File inquiry operators (q.v.) and a filetest builtin which uses them.

       A variety of Automatic, periodic and timed events (q.v.) including scheduled events, special aliases, automatic
       logout and terminal locking, command timing and watching for logins and logouts.

       Support for the Native Language System (see Native Language System support), OS variant features (see OS  vari-
       ant support and the echo_style shell variable) and system-dependent file locations (see FILES).

       Extensive terminal-management capabilities.  See Terminal management.

       New builtin commands including builtins, hup, ls-F, newgrp, printenv, which and where (q.v.).

       New  variables  that  make useful information easily available to the shell.  See the gid, loginsh, oid, shlvl,
       tcsh, tty, uid and version shell variables and the HOST, REMOTEHOST, VENDOR, OSTYPE  and  MACHTYPE  environment
       variables.

       A new syntax for including useful information in the prompt string (see prompt).  and special prompts for loops
       and spelling correction (see prompt2 and prompt3).

       Read-only variables.  See Variable substitution.

BUGS
       When a suspended command is restarted, the shell prints the directory it started in if this is  different  from
       the  current  directory.   This  can be misleading (i.e., wrong) as the job may have changed directories inter-
       nally.

       Shell builtin functions are not stoppable/restartable.  Command sequences of the form 'a ; b ; c' are also  not
       handled  gracefully  when  stopping  is attempted.  If you suspend 'b', the shell will then immediately execute
       'c'.  This is especially noticeable if this expansion results from an alias.  It suffices to place the sequence
       of commands in ()'s to force it to a subshell, i.e., '( a ; b ; c )'.

       Control  over tty output after processes are started is primitive; perhaps this will inspire someone to work on
       a good virtual terminal interface.  In a virtual terminal interface much more interesting things could be  done
       with output control.

       Alias  substitution  is  most often used to clumsily simulate shell procedures; shell procedures should be pro-
       vided rather than aliases.

       Commands within loops are not placed in the history list.  Control structures  should  be  parsed  rather  than
       being recognized as built-in commands.  This would allow control commands to be placed anywhere, to be combined
       with '|', and to be used with '&' and ';' metasyntax.

       foreach doesn't ignore here documents when looking for its end.

       It should be possible to use the ':' modifiers on the output of command substitutions.

       The screen update for lines longer than the screen width is very poor if the terminal cannot move the cursor up
       (i.e., terminal type 'dumb').

       HPATH and NOREBIND don't need to be environment variables.

       Glob-patterns which do not use '?', '*' or '[]' or which use '{}' or '~' are not negated correctly.

       The  single-command  form  of if does output redirection even if the expression is false and the command is not
       executed.

       ls-F includes file identification characters when sorting filenames and does not handle control  characters  in
       filenames well.  It cannot be interrupted.

       Command substitution supports multiple commands and conditions, but not cycles or backward gotos.

       Report  bugs  at  http://bugs.gw.com/, preferably with fixes.  If you want to help maintain and test tcsh, send
       mail to tcsh-requestATmx.com with the text 'subscribe tcsh' on a line by itself in the body.

THE T IN TCSH
       In 1964, DEC produced the PDP-6.  The PDP-10 was a later re-implementation.  It was re-christened  the  DECsys-
       tem-10 in 1970 or so when DEC brought out the second model, the KI10.

       TENEX was created at Bolt, Beranek & Newman (a Cambridge, Massachusetts think tank) in 1972 as an experiment in
       demand-paged virtual memory operating systems.  They built a new pager for the DEC PDP-10 and created the OS to
       go with it.  It was extremely successful in academia.

       In  1975,  DEC  brought out a new model of the PDP-10, the KL10; they intended to have only a version of TENEX,
       which they had licensed from BBN, for the new box.  They called their version TOPS-20 (their capitalization  is
       trademarked).   A  lot of TOPS-10 users ('The OPerating System for PDP-10') objected; thus DEC found themselves
       supporting two incompatible systems on the same hardware--but then there were 6 on the PDP-11!

       TENEX, and TOPS-20 to version 3, had command completion via a user-code-level subroutine library called ULTCMD.
       With version 3, DEC moved all that capability and more into the monitor ('kernel' for you Unix types), accessed
       by the COMND% JSYS ('Jump to SYStem' instruction, the supervisor call mechanism [are my IBM  roots  also  show-
       ing?]).

       The  creator  of tcsh was impressed by this feature and several others of TENEX and TOPS-20, and created a ver-
       sion of csh which mimicked them.

LIMITATIONS
       The system limits argument lists to ARG_MAX characters.

       The number of arguments to a command which involves filename expansion is limited to 1/6th the number of  char-
       acters allowed in an argument list.

       Command substitutions may substitute no more characters than are allowed in an argument list.

       To detect looping, the shell restricts the number of alias substitutions on a single line to 20.

SEE ALSO
       csh(1),  emacs(1),  ls(1),  newgrp(1),  sh(1),  setpath(1),  stty(1),  su(1),  tset(1), vi(1), x(1), access(2),
       execve(2), fork(2), killpg(2), pipe(2), setrlimit(2), sigvec(2), stat(2),  umask(2),  vfork(2),  wait(2),  mal-
       loc(3), setlocale(3), tty(4), a.out(5), termcap(5), environ(7), termio(7), Introduction to the C Shell

VERSION
       This manual documents tcsh 6.17.00 (Astron) 2009-07-10.

AUTHORS
       William Joy
         Original author of csh(1)
       J.E. Kulp, IIASA, Laxenburg, Austria
         Job control and directory stack features
       Ken Greer, HP Labs, 1981
         File name completion
       Mike Ellis, Fairchild, 1983
         Command name recognition/completion
       Paul Placeway, Ohio State CIS Dept., 1983-1993
         Command line editor, prompt routines, new glob syntax and numerous fixes and speedups
       Karl Kleinpaste, CCI 1983-4
         Special  aliases, directory stack extraction stuff, login/logout watch, scheduled events, and the idea of the
         new prompt format
       Rayan Zachariassen, University of Toronto, 1984
         ls-F and which builtins and numerous bug fixes, modifications and speedups
       Chris Kingsley, Caltech
         Fast storage allocator routines
       Chris Grevstad, TRW, 1987
         Incorporated 4.3BSD csh into tcsh
       Christos S. Zoulas, Cornell U. EE Dept., 1987-94
         Ports to HPUX, SVR2 and SVR3, a SysV version of getwd.c, SHORT_STRINGS support and a new version of sh.glob.c
       James J Dempsey, BBN, and Paul Placeway, OSU, 1988
         A/UX port
       Daniel Long, NNSC, 1988
         wordchars
       Patrick Wolfe, Kuck and Associates, Inc., 1988
         vi mode cleanup
       David C Lawrence, Rensselaer Polytechnic Institute, 1989
         autolist and ambiguous completion listing
       Alec Wolman, DEC, 1989
         Newlines in the prompt
       Matt Landau, BBN, 1989
         ~/.tcshrc
       Ray Moody, Purdue Physics, 1989
         Magic space bar history expansion
       Mordechai ????, Intel, 1989
         printprompt() fixes and additions
       Kazuhiro Honda, Dept. of Computer Science, Keio University, 1989
         Automatic spelling correction and prompt3
       Per Hedeland, Ellemtel, Sweden, 1990-
         Various bugfixes, improvements and manual updates
       Hans J. Albertsson (Sun Sweden)
         ampm, settc and telltc
       Michael Bloom
         Interrupt handling fixes
       Michael Fine, Digital Equipment Corp
         Extended key support
       Eric Schnoebelen, Convex, 1990
         Convex support, lots of csh bug fixes, save and restore of directory stack
       Ron Flax, Apple, 1990
         A/UX 2.0 (re)port
       Dan Oscarsson, LTH Sweden, 1990
         NLS support and simulated NLS support for non NLS sites, fixes
       Johan Widen, SICS Sweden, 1990
         shlvl, Mach support, correct-line, 8-bit printing
       Matt Day, Sanyo Icon, 1990
         POSIX termio support, SysV limit fixes
       Jaap Vermeulen, Sequent, 1990-91
         Vi mode fixes, expand-line, window change fixes, Symmetry port
       Martin Boyer, Institut de recherche d'Hydro-Quebec, 1991
         autolist  beeping  options,  modified the history search to search for the whole string from the beginning of
         the line to the cursor.
       Scott Krotz, Motorola, 1991
         Minix port
       David Dawes, Sydney U. Australia, Physics Dept., 1991
         SVR4 job control fixes
       Jose Sousa, Interactive Systems Corp., 1991
         Extended vi fixes and vi delete command
       Marc Horowitz, MIT, 1991
         ANSIfication fixes, new exec hashing code, imake fixes, where
       Bruce Sterling Woodcock, sterlingATnetcom.com, 1991-1995
         ETA and Pyramid port, Makefile and lint fixes, ignoreeof=n addition, and various  other  portability  changes
         and bug fixes
       Jeff Fink, 1992
         complete-word-fwd and complete-word-back
       Harry C. Pulley, 1992
         Coherent port
       Andy Phillips, Mullard Space Science Lab U.K., 1992
         VMS-POSIX port
       Beto Appleton, IBM Corp., 1992
         Walking process group fixes, csh bug fixes, POSIX file tests, POSIX SIGHUP
       Scott Bolte, Cray Computer Corp., 1992
         CSOS port
       Kaveh R. Ghazi, Rutgers University, 1992
         Tek, m88k, Titan and Masscomp ports and fixes.  Added autoconf support.
       Mark Linderman, Cornell University, 1992
         OS/2 port
       Mika Liljeberg, liljeberATkruuna.FI, 1992
         Linux port
       Tim P. Starrin, NASA Langley Research Center Operations, 1993
         Read-only variables
       Dave Schweisguth, Yale University, 1993-4
         New man page and tcsh.man2html
       Larry Schwimmer, Stanford University, 1993
         AFS and HESIOD patches
       Luke Mewburn, RMIT University, 1994-6
         Enhanced directory printing in prompt, added ellipsis and rprompt.
       Edward Hutchins, Silicon Graphics Inc., 1996
         Added implicit cd.
       Martin Kraemer, 1997
         Ported to Siemens Nixdorf EBCDIC machine
       Amol Deshpande, Microsoft, 1997
         Ported to WIN32 (Windows/95 and Windows/NT); wrote all the missing library and message catalog code to inter-
         face to Windows.
       Taga Nayuta, 1998
         Color ls additions.


THANKS TO
       Bryan Dunlap, Clayton Elwell, Karl Kleinpaste, Bob Manson, Steve Romig, Diana Smetters, Bob  Sutterfield,  Mark
       Verber, Elizabeth Zwicky and all the other people at Ohio State for suggestions and encouragement

       All  the  people  on  the net, for putting up with, reporting bugs in, and suggesting new additions to each and
       every version

       Richard M. Alderson III, for writing the 'T in tcsh' section



Astron 6.17.00                   10 July 2009                          TCSH(1)