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GETOPT(1)                                                            GETOPT(1)



NAME
       getopt - parse command options (enhanced)

SYNOPSIS
       getopt optstring parameters
       getopt [options] [--] optstring parameters
       getopt [options] -o|--options optstring [options] [--] parameters

DESCRIPTION
       getopt  is used to break up (parse) options in command lines for easy parsing by shell procedures, and to check
       for legal options.  It uses the GNU getopt(3) routines to do this.

       The parameters getopt is called with can be divided into two parts: options which modify the  way  getopt  will
       parse  (options and -o|--options optstring in the SYNOPSIS), and the parameters which are to be parsed (parame-
       ters in the SYNOPSIS).  The second part will start at the first non-option parameter  that  is  not  an  option
       argument,  or after the first occurrence of '--'.  If no '-o' or '--options' option is found in the first part,
       the first parameter of the second part is used as the short options string.

       If the environment variable GETOPT_COMPATIBLE is set, or if its first parameter is  not  an  option  (does  not
       start  with  a  '-',  this is the first format in the SYNOPSIS), getopt will generate output that is compatible
       with that of other versions of getopt(1).  It will still do parameter shuffling and  recognize  optional  argu-
       ments (see section COMPATIBILITY for more information).

       Traditional  implementations of getopt(1) are unable to cope with whitespace and other (shell-specific) special
       characters in arguments and non-option parameters. To solve this  problem,  this  implementation  can  generate
       quoted  output  which must once again be interpreted by the shell (usually by using the eval command). This has
       the effect of preserving those characters, but you must call getopt in a way that is no longer compatible  with
       other  versions  (the  second  or third format in the SYNOPSIS).  To determine whether this enhanced version of
       getopt(1) is installed, a special test option (-T) can be used.

OPTIONS
       -a, --alternative
              Allow long options to start with a single '-'.

       -h, --help
              Output a small usage guide and exit successfully. No other output is generated.

       -l, --longoptions longopts
              The long (multi-character) options to be recognized.  More than one option  name  may  be  specified  at
              once,  by  separating  the  names with commas. This option may be given more than once, the longopts are
              cumulative.  Each long option name in longopts may be followed  by  one  colon  to  indicate  it  has  a
              required argument, and by two colons to indicate it has an optional argument.

       -n, --name progname
              The  name  that  will  be  used  by  the  getopt(3) routines when it reports errors. Note that errors of
              getopt(1) are still reported as coming from getopt.

       -o, --options shortopts
              The short (one-character) options to be recognized. If this option is not found, the first parameter  of
              getopt  that  does  not  start  with  a '-' (and is not an option argument) is used as the short options
              string.  Each short option character in shortopts may be followed by one colon  to  indicate  it  has  a
              required  argument,  and  by two colons to indicate it has an optional argument.  The first character of
              shortopts may be '+' or '-' to influence the way options are parsed and output is generated (see section
              SCANNING MODES for details).

       -q, --quiet
              Disable error reporting by getopt(3).

       -Q, --quiet-output
              Do not generate normal output. Errors are still reported by getopt(3), unless you also use -q.

       -s, --shell shell
              Set  quoting  conventions  to those of shell. If no -s argument is found, the BASH conventions are used.
              Valid arguments are currently 'sh' 'bash', 'csh', and 'tcsh'.

       -u, --unquoted
              Do not quote the output. Note that whitespace and special (shell-dependent) characters can  cause  havoc
              in this mode (like they do with other getopt(1) implementations).

       -T, --test
              Test  if  your  getopt(1) is this enhanced version or an old version. This generates no output, and sets
              the error status to 4. Other implementations of getopt(1), and this version if the environment  variable
              GETOPT_COMPATIBLE is set, will return '--' and error status 0.

       -V, --version
              Output version information and exit successfully. No other output is generated.

PARSING
       This  section specifies the format of the second part of the parameters of getopt (the parameters in the SYNOP-
       SIS).  The next section (OUTPUT) describes the output that is generated. These parameters  were  typically  the
       parameters  a  shell  function  was called with.  Care must be taken that each parameter the shell function was
       called with corresponds to exactly one parameter in the parameter list of getopt (see the EXAMPLES).  All pars-
       ing is done by the GNU getopt(3) routines.

       The parameters are parsed from left to right. Each parameter is classified as a short option, a long option, an
       argument to an option, or a non-option parameter.

       A simple short option is a '-' followed by a short option character. If the option has a required argument,  it
       may be written directly after the option character or as the next parameter (ie. separated by whitespace on the
       command line). If the option has an optional argument, it must be written directly after the  option  character
       if present.

       It is possible to specify several short options after one '-', as long as all (except possibly the last) do not
       have required or optional arguments.

       A long option normally begins with '--' followed by the long option name.  If the option has a  required  argu-
       ment,  it  may  be  written directly after the long option name, separated by '=', or as the next argument (ie.
       separated by whitespace on the command line).  If the option has an  optional  argument,  it  must  be  written
       directly after the long option name, separated by '=', if present (if you add the '=' but nothing behind it, it
       is interpreted as if no argument was present; this is a slight bug, see the BUGS).  Long options may be  abbre-
       viated, as long as the abbreviation is not ambiguous.

       Each  parameter  not  starting  with  a  '-', and not a required argument of a previous option, is a non-option
       parameter. Each parameter after a '--' parameter is always interpreted as a non-option parameter.  If the envi-
       ronment variable POSIXLY_CORRECT is set, or if the short option string started with a '+', all remaining param-
       eters are interpreted as non-option parameters as soon as the first non-option parameter is found.

OUTPUT
       Output is generated for each element described in the previous section.  Output is done in the  same  order  as
       the  elements  are  specified  in the input, except for non-option parameters. Output can be done in compatible
       (unquoted) mode, or in such way that whitespace and other special characters within  arguments  and  non-option
       parameters  are  preserved (see QUOTING).  When the output is processed in the shell script, it will seem to be
       composed of distinct elements that can be processed one by one (by using the shift command in most  shell  lan-
       guages).  This  is  imperfect  in  unquoted mode, as elements can be split at unexpected places if they contain
       whitespace or special characters.

       If there are problems parsing the parameters, for example because a required argument is not found or an option
       is  not recognized, an error will be reported on stderr, there will be no output for the offending element, and
       a non-zero error status is returned.

       For a short option, a single '-' and the option character are generated as one parameter. If the option has  an
       argument,  the  next  parameter  will  be  the argument. If the option takes an optional argument, but none was
       found, the next parameter will be generated but be empty in quoting mode, but no second parameter will be  gen-
       erated  in  unquoted (compatible) mode.  Note that many other getopt(1) implementations do not support optional
       arguments.

       If several short options were specified after a single '-', each will be present in the output  as  a  separate
       parameter.

       For  a  long  option,  '--'  and  the  full option name are generated as one parameter. This is done regardless
       whether the option was abbreviated or specified with a single '-' in the input. Arguments are handled  as  with
       short options.

       Normally,  no  non-option parameters output is generated until all options and their arguments have been gener-
       ated. Then '--' is generated as a single parameter, and after it the non-option parameters in  the  order  they
       were  found,  each as a separate parameter.  Only if the first character of the short options string was a '-',
       non-option parameter output is generated at the place they are found in the input (this is not supported if the
       first format of the SYNOPSIS is used; in that case all preceding occurrences of '-' and '+' are ignored).

QUOTING
       In  compatible  mode,  whitespace or 'special' characters in arguments or non-option parameters are not handled
       correctly. As the output is fed to the shell script, the script does not know how it is supposed to  break  the
       output  into  separate parameters.  To circumvent this problem, this implementation offers quoting. The idea is
       that output is generated with quotes around each parameter. When this output is once again  fed  to  the  shell
       (usually by a shell eval command), it is split correctly into separate parameters.

       Quoting  is not enabled if the environment variable GETOPT_COMPATIBLE is set, if the first form of the SYNOPSIS
       is used, or if the option '-u' is found.

       Different shells use different quoting conventions. You can use the '-s' option to select  the  shell  you  are
       using.  The following shells are currently supported: 'sh', 'bash', 'csh' and 'tcsh'.  Actually, only two 'fla-
       vors' are distinguished: sh-like quoting conventions and csh-like quoting conventions. Chances are that if  you
       use another shell script language, one of these flavors can still be used.


SCANNING MODES
       The  first  character of the short options string may be a '-' or a '+' to indicate a special scanning mode. If
       the first calling form in the SYNOPSIS is used they are ignored; the environment  variable  POSIXLY_CORRECT  is
       still examined, though.

       If  the first character is '+', or if the environment variable POSIXLY_CORRECT is set, parsing stops as soon as
       the first non-option parameter (ie. a parameter that does not start with a '-') is found that is not an  option
       argument. The remaining parameters are all interpreted as non-option parameters.

       If the first character is a '-', non-option parameters are outputted at the place where they are found; in nor-
       mal operation, they are all collected at the end of output after a '--' parameter has been generated. Note that
       this '--' parameter is still generated, but it will always be the last parameter in this mode.

COMPATIBILITY
       This  version  of  getopt(1) is written to be as compatible as possible to other versions. Usually you can just
       replace them with this version without any modifications, and with some advantages.

       If the first character of the first parameter of getopt is not a '-', getopt goes into compatibility  mode.  It
       will  interpret  its first parameter as the string of short options, and all other arguments will be parsed. It
       will still do parameter shuffling (ie. all non-option parameters are outputted at the end), unless the environ-
       ment variable POSIXLY_CORRECT is set.

       The environment variable GETOPT_COMPATIBLE forces getopt into compatibility mode. Setting both this environment
       variable and POSIXLY_CORRECT offers 100% compatibility for 'difficult' programs. Usually,  though,  neither  is
       needed.

       In compatibility mode, leading '-' and '+' characters in the short options string are ignored.

RETURN CODES
       getopt  returns error code 0 for successful parsing, 1 if getopt(3) returns errors, 2 if it does not understand
       its own parameters, 3 if an internal error occurs like out-of-memory, and 4 if it is called with -T.

EXAMPLES
       Example scripts for (ba)sh and (t)csh  are  provided  with  the  getopt(1)  distribution,  and  are  optionally
       installed in /usr/share/getopt.


ENVIRONMENT
       POSIXLY_CORRECT
              This environment variable is examined by the getopt(3) routines.  If it is set, parsing stops as soon as
              a parameter is found that is not an option or an option argument.  All  remaining  parameters  are  also
              interpreted as non-option parameters, regardless whether they start with a '-'.

       GETOPT_COMPATIBLE
              Forces getopt to use the first calling format as specified in the SYNOPSIS.

BUGS
       getopt(3) can parse long options with optional arguments that are given an empty optional argument (but can not
       do this for short options). This getopt(1) treats optional arguments  that  are  empty  as  if  they  were  not
       present.

       The  syntax  if  you  do not want any short option variables at all is not very intuitive (you have to set them
       explicitly to the empty string).


AUTHOR
       Frodo Looijaard <frodoATfrodo.name>

SEE ALSO
       getopt(3), bash(1), tcsh(1).

AVAILABILITY
       The  getopt  command  is  part  of  the  util-linux-ng   package   and   is   available   from   ftp://ftp.ker-
       nel.org/pub/linux/utils/util-linux-ng/.



Linux                            May 31, 1997                        GETOPT(1)