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       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (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 Section 2.3.1, 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 POSIX.1‐2017, the alias definition shall not affect the parent process of  the  current
       shell  nor any utility environment invoked by the shell; see Section 2.12, 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  POSIX.1‐2017,  Section  8.2,
                 Internationalization  Variables  for  the  precedence  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 example, 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 written 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 Section 2.2, 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. Create a short alias for a commonly used ls command:

               alias lf="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 POSIX.1‐2017, 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  POSIX.1‐2017  only  when  an  explicit extension such as -x is used. The
       standard developers considered that aliases were of use primarily to interactive users and
       that  they  should  normally not affect shell scripts called by those users; functions 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 POSIX.1‐2017 has made this a requirement for
       all similar output. Therefore, consistency was  chosen  over  this  detail  of  historical
       practice.

FUTURE DIRECTIONS

       None.

SEE ALSO

       Section 2.9.5, Function Definition Command

       The Base Definitions volume of POSIX.1‐2017, Chapter 8, Environment Variables

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1-2017, Standard for Information Technology -- Portable  Operating  System  Interface
       (POSIX),  The  Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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
       Standard, 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 .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .