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ALIAS(1P)                  POSIX Programmer's Manual                 ALIAS(1P)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may dif-
       fer (consult the corresponding Linux manual page for details of Linux behavior), or the interface  may  not  be
       implemented on Linux.

NAME
       alias - define or display aliases

SYNOPSIS
       alias [alias-name[=string] ...]

DESCRIPTION
       The  alias utility shall create or redefine alias definitions or write the values of existing alias definitions
       to standard output. An alias definition provides a string value that shall replace a command name  when  it  is
       encountered; see Alias Substitution .

       An  alias definition shall affect the current shell execution environment and the execution environments of the
       subshells of the current shell. When used as specified by this volume of IEEE Std 1003.1-2001, the alias  defi-
       nition  shall  not  affect  the  parent process of the current shell nor any utility environment invoked by the
       shell; see Shell Execution Environment .

OPTIONS
       None.

OPERANDS
       The following operands shall be supported:

       alias-name
              Write the alias definition to standard output.

       alias-name=string

              Assign the value of string to the alias alias-name.


       If no operands are given, all alias definitions shall be written to standard output.

STDIN
       Not used.

INPUT FILES
       None.

ENVIRONMENT VARIABLES
       The following environment variables shall affect the execution of alias:

       LANG   Provide a default value for the internationalization variables that are unset or  null.  (See  the  Base
              Definitions  volume  of IEEE Std 1003.1-2001, Section 8.2, Internationalization Variables for the prece-
              dence of internationalization variables used to determine the values of locale categories.)

       LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables.

       LC_CTYPE
              Determine  the locale for the interpretation of sequences of bytes of text data as characters (for exam-
              ple, single-byte as opposed to multi-byte characters in arguments).

       LC_MESSAGES
              Determine the locale that should be used to affect the format and contents of diagnostic messages  writ-
              ten to standard error.

       NLSPATH
              Determine the location of message catalogs for the processing of LC_MESSAGES .


ASYNCHRONOUS EVENTS
       Default.

STDOUT
       The format for displaying aliases (when no operands or only name operands are specified) shall be:


              "%s=%s\n", name, value

       The value string shall be written with appropriate quoting so that it is suitable for reinput to the shell. See
       the description of shell quoting in Quoting .

STDERR
       The standard error shall be used only for diagnostic messages.

OUTPUT FILES
       None.

EXTENDED DESCRIPTION
       None.

EXIT STATUS
       The following exit values shall be returned:

        0     Successful completion.

       >0     One of the name operands specified did not have an alias definition, or an error occurred.


CONSEQUENCES OF ERRORS
       Default.

       The following sections are informative.

APPLICATION USAGE
       None.

EXAMPLES
        1. Change ls to give a columnated, more annotated output:


           alias ls="ls -CF"


        2. Create a simple "redo" command to repeat previous entries in the command history file:


           alias r='fc -s'


        3. Use 1K units for du:


           alias du=du\ -k


        4. Set up nohup so that it can deal with an argument that is itself an alias name:


           alias nohup="nohup "


RATIONALE
       The alias description is based on historical KornShell implementations.  Known differences exist  between  that
       and  the  C  shell. The KornShell version was adopted to be consistent with all the other KornShell features in
       this volume of IEEE Std 1003.1-2001, such as command line editing.

       Since alias affects the current shell execution environment, it is generally provided as a shell regular built-
       in.

       Historical  versions  of  the  KornShell have allowed aliases to be exported to scripts that are invoked by the
       same shell. This is triggered by the alias -x flag; it is allowed by this volume of  IEEE Std 1003.1-2001  only
       when an explicit extension such as -x is used. The standard developers considered that aliases were of use pri-
       marily to interactive users and that they should normally not affect shell scripts called by those users; func-
       tions are available to such scripts.

       Historical  versions  of  the  KornShell had not written aliases in a quoted manner suitable for reentry to the
       shell, but this volume of IEEE Std 1003.1-2001 has made this a requirement for all similar  output.  Therefore,
       consistency with this volume of IEEE Std 1003.1-2001 was chosen over this detail of historical practice.

FUTURE DIRECTIONS
       None.

SEE ALSO
       Function Definition Command

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Stan-
       dard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base  Specifica-
       tions  Issue  6,  Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The
       Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Stan-
       dard,  the  original  IEEE  and  The  Open Group Standard is the referee document. The original Standard can be
       obtained online at http://www.opengroup.org/unix/online.html .



IEEE/The Open Group                  2003                            ALIAS(1P)