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PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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ALIAS(1P) POSIX Programmer's Manual ALIAS(1P)
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.
alias — define or display aliases
alias [alias-name[=string]...]
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.
None.
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.
Not used.
None.
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.
Default.
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.
The standard error shall be used only for diagnostic messages.
None.
None.
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.
Default.
The following sections are informative.
None.
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 "
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.
None.
Section 2.9.5, Function Definition Command
The Base Definitions volume of POSIX.1‐2017, Chapter 8,
Environment Variables
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 .
IEEE/The Open Group 2017 ALIAS(1P)
Pages that refer to this page: unalias(1p)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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