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       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
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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.1‐2008,  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.1‐2008, 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.1‐2008, 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.1‐2008 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.1‐2008 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.1‐2008, Chapter 8, Environment Variables

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
       Standard  for  Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers,  Inc
       and  The  Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html .

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