ALIAS(1) User Commands ALIAS(1)


NAME


alias, unalias - create or remove a pseudonym or shorthand for a command
or series of commands

SYNOPSIS


/usr/bin/alias [alias-name[= string...]]


/usr/bin/unalias alias-name...


/usr/bin/unalias -a


csh
alias [name [def]]


unalias pattern


ksh
alias [-tx] [name[= value]...]


unalias name...


unalias [-a]


ksh93
alias [-ptx] [name[= value]...]


unalias [-a] [name...]


DESCRIPTION


The alias and unalias utilities create or remove a pseudonym or shorthand
term for a command or series of commands, with different functionality in
the C-shell and Korn shell environments.

/usr/bin/alias
The alias utility creates or redefines alias definitions or writes the
values of existing alias definitions to standard output. An alias
definition provides a string value that replaces a command name when it
is encountered.


An alias definition affects the current shell execution environment and
the execution environments of the subshells of the current shell. When
used as specified by this document, the alias definition does not affect
the parent process of the current shell nor any utility environment
invoked by the shell.

/usr/bin/unalias
The unalias utility removes the definition for each alias name specified.
The aliases are removed from the current shell execution environment. The
-a option removes all alias definitions from the current execution
environment.

csh
alias assigns def to the alias name. The assigned def is a list of words
that can contain escaped history-substitution metasyntax. name is not
allowed to be alias or unalias. If def is omitted, the alias name is
displayed along with its current definition. If both name and def are
omitted, all aliases are displayed.


Because of implementation restrictions, an alias definition must have
been entered on a previous command line before it can be used.


unalias discards aliases that match (filename substitution) pattern. All
aliases can be removed by `unalias *'.

ksh
alias with no arguments prints the list of aliases in the form name=value
on standard output. An alias is defined for each name whose value is
specified. A trailing space in value causes the next word to be checked
for alias substitution. The -t flag is used to set and list tracked
aliases. The value of a tracked alias is the full pathname corresponding
to the specified name. The value becomes undefined when the value of PATH
is reset but the aliases remained tracked. Without the -t flag, for each
name in the argument list for which no value is specified, the name and
value of the alias is printed. The -x flag is used to set or print
exported aliases. An exported alias is defined for scripts invoked by
name. The exit status is non-zero if a name is specified, but no value,
and no alias has been defined for the name.


The aliass specified by the list of names can be removed from the alias
list with unalias.

ksh93
alias creates or redefines alias definitions or writes the existing alias
definitions to standard output.


An alias definition provides a string value that replaces a command name
when the command is read. Alias names can contain any printable character
that is not special to the shell. If an alias value ends in a SPACE or
TAB, the word following the command name the alias replaces is also
checked to see whether it is an alias.


If no names are specified, the names and values of all aliases are
written to standard output. Otherwise, for each name that is specified,
and =value is not specified, the current value of the alias corresponding
to name is written to standard output. If =value is specified, the alias
name is created or redefined.


alias is built-in to the shell as a declaration command so that field
splitting and pathname expansion are not performed on the arguments.
Tilde expansion occurs on value. An alias definition only affects scripts
read by the current shell environment. It does not affect scripts run by
this shell.


unalias removes the definition of each named alias from the current shell
execution environment, or all aliases if -a is specified. It does not
affect any commands that have already been read and subsequently
executed.

OPTIONS


The following option is supported by unalias:

-a
Removes all alias definitions from the current shell execution
environment.


ksh
The following option is supported by alias:

-t
Sets and lists tracked aliases.


ksh93
The following options are supported by alias:

-p
Causes the output to be in the form of alias commands that can be
used as input to the shell to recreate the current aliases.


-t
Specifies tracked aliases.

Tracked aliases connect a command name to the command's pathname,
and are reset when the PATH variable is unset. The tracked aliases
feature is now obsolete.


-x
Ignored, this option is obsolete.


The following option is supported by unalias:

-a
Causes all alias definitions to be removed. name operands are
optional and ignored if specified.


OPERANDS


The following operands are supported:

alias
alias-name
Write the alias definition to standard output.


unalias
alias-name
The name of an alias to be removed.


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


If no operands are specified, all alias definitions are written to
standard output.

OUTPUT


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

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


The value string is written with appropriate quoting so that it is
suitable for reinput to the shell.

EXAMPLES


Example 1: Modifying a Command's Output




This example specifies that the output of the ls utility is columnated
and more annotated:


example% alias ls="ls -CF"


Example 2: Repeating Previous Entries in the Command History File




This example creates a simple "redo" command to repeat previous entries
in the command history file:


example% alias r='fc -s'


Example 3: Specifying a Command's Output Options




This example provides that the du utility summarize disk output in units
of 1024 bytes:


example% alias du=du -k


Example 4: Dealing with an Argument That is an Alias Name




This example sets up the nohup utility so that it can deal with an
argument that is an alias name:


example% alias nohup="nohup "


ENVIRONMENT VARIABLES


See environ(7) for descriptions of the following environment variables
that affect the execution of alias and unalias: LANG, LC_ALL, LC_CTYPE,
LC_MESSAGES, and NLSPATH.

EXIT STATUS


The following exit values are returned:

0
Successful completion.


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


unalias
>0
One of the alias-name operands specified did not represent a valid
alias definition, or an error occurred.


ATTRIBUTES


See attributes(7) for descriptions of the following attributes:

csh, ksh


+--------------------+-------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------+
|Interface Stability | Committed |
+--------------------+-------------------+
|Standard | See standards(7). |
+--------------------+-------------------+

ksh93


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Uncommitted |
+--------------------+-----------------+

SEE ALSO


csh(1), ksh(1), ksh93(1), shell_builtins(1), attributes(7), environ(7),
standards(7)


April 8, 2008 ALIAS(1)