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.TH ALIAS 1 "Apr 8, 2008"
.SH NAME
alias, unalias \- create or remove a pseudonym or shorthand for a command or
series of commands
.SH SYNOPSIS
.LP
.nf
\fB/usr/bin/alias\fR [\fIalias-name\fR[= \fIstring\fR...]]
.fi

.LP
.nf
\fB/usr/bin/unalias\fR \fIalias-name\fR...
.fi

.LP
.nf
\fB/usr/bin/unalias\fR \fB-a\fR
.fi

.SS "\fBcsh\fR"
.LP
.nf
\fBalias\fR [\fIname\fR [\fIdef\fR]]
.fi

.LP
.nf
\fBunalias\fR \fIpattern\fR
.fi

.SS "\fBksh\fR"
.LP
.nf
\fBalias\fR [\fB-tx\fR] [\fIname\fR[= \fIvalue\fR]...]
.fi

.LP
.nf
\fBunalias\fR \fIname\fR...
.fi

.LP
.nf
\fBunalias\fR [\fB-a\fR]
.fi

.SS "\fBksh93\fR"
.LP
.nf
\fBalias\fR [\fB-ptx\fR] [\fIname\fR[= \fIvalue\fR]...]
.fi

.LP
.nf
\fBunalias\fR [\fB-a\fR] [\fIname\fR...]
.fi

.SH DESCRIPTION
.sp
.LP
The \fBalias\fR and \fBunalias\fR 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.
.SS "\fB/usr/bin/alias\fR"
.sp
.LP
The \fBalias\fR 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.
.sp
.LP
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.
.SS "\fB/usr/bin/unalias\fR"
.sp
.LP
The \fBunalias\fR utility removes the definition for each alias name specified.
The aliases are removed from the current shell execution environment. The
\fB-a\fR option removes all alias definitions from the current execution
environment.
.SS "\fBcsh\fR"
.sp
.LP
\fBalias\fR assigns \fIdef\fR to the alias \fIname\fR. The assigned \fIdef\fR
is a list of words that can contain escaped history-substitution metasyntax.
\fIname\fR is not allowed to be \fBalias\fR or \fBunalias\fR. If \fIdef\fR is
omitted, the alias \fIname\fR is displayed along with its current definition.
If both \fIname\fR and \fIdef\fR are omitted, all aliases are displayed.
.sp
.LP
Because of implementation restrictions, an alias definition must have been
entered on a previous command line before it can be used.
.sp
.LP
\fBunalias\fR discards aliases that match (filename substitution)
\fIpattern\fR. All aliases can be removed by `\fBunalias *\fR'.
.SS "\fBksh\fR"
.sp
.LP
\fBalias\fR with no arguments prints the list of aliases in the form
\fIname=value\fR on standard output. An \fBalias\fR is defined for each name
whose \fIvalue\fR is specified. A trailing space in \fIvalue\fR causes the next
word to be checked for alias substitution. The \fB-t\fR flag is used to set and
list tracked aliases. The value of a tracked alias is the full pathname
corresponding to the specified \fIname\fR. The value becomes undefined when the
value of \fBPATH\fR is reset but the aliases remained tracked. Without the
\fB-t\fR flag, for each \fIname\fR in the argument list for which no
\fIvalue\fR is specified, the name and value of the alias is printed. The
\fB-x\fR flag is used to set or print \fIexported alias\fRes. An exported alias
is defined for scripts invoked by \fIname\fR. The exit status is non-zero if a
\fIname\fR is specified, but no value, and no alias has been defined for the
\fIname\fR.
.sp
.LP
The \fBalias\fRs specified by the list of \fIname\fRs can be removed from the
\fBalias\fR list with \fBunalias\fR.
.SS "\fBksh93\fR"
.sp
.LP
\fBalias\fR creates or redefines alias definitions or writes the existing alias
definitions to standard output.
.sp
.LP
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.
.sp
.LP
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
\fB=\fR\fIvalue\fR is not specified, the current value of the alias
corresponding to name is written to standard output. If \fB=\fR\fIvalue\fR is
specified, the alias name is created or redefined.
.sp
.LP
\fBalias\fR 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 \fIvalue\fR. An alias definition only affects scripts read
by the current shell environment. It does not affect scripts run by this shell.
.sp
.LP
\fBunalias\fR removes the definition of each named alias from the current shell
execution environment, or all aliases if \fB-a\fR is specified. It does not
affect any commands that have already been read and subsequently executed.
.SH OPTIONS
.sp
.LP
The following option is supported by \fBunalias\fR:
.sp
.ne 2
.na
\fB\fB-a\fR\fR
.ad
.RS 6n
Removes all alias definitions from the current shell execution environment.
.RE

.SS "\fBksh\fR"
.sp
.LP
The following option is supported by \fBalias\fR:
.sp
.ne 2
.na
\fB\fB-t\fR\fR
.ad
.RS 6n
Sets and lists tracked aliases.
.RE

.SS "\fBksh93\fR"
.sp
.LP
The following options are supported by \fBalias\fR:
.sp
.ne 2
.na
\fB\fB-p\fR\fR
.ad
.RS 6n
Causes the output to be in the form of \fBalias\fR commands that can be used as
input to the shell to recreate the current aliases.
.RE

.sp
.ne 2
.na
\fB\fB-t\fR\fR
.ad
.RS 6n
Specifies tracked aliases.
.sp
Tracked aliases connect a command name to the command's pathname, and are reset
when the \fBPATH\fR variable is unset. The tracked aliases feature is now
obsolete.
.RE

.sp
.ne 2
.na
\fB\fB-x\fR\fR
.ad
.RS 6n
Ignored, this option is obsolete.
.RE

.sp
.LP
The following option is supported by \fBunalias\fR:
.sp
.ne 2
.na
\fB\fB-a\fR\fR
.ad
.RS 6n
Causes all alias definitions to be removed. \fIname\fR operands are optional
and ignored if specified.
.RE

.SH OPERANDS
.sp
.LP
The following operands are supported:
.SS "\fBalias\fR"
.sp
.ne 2
.na
\fB\fIalias-name\fR\fR
.ad
.RS 14n
Write the alias definition to standard output.
.RE

.SS "\fBunalias\fR"
.sp
.ne 2
.na
\fB\fIalias-name\fR\fR
.ad
.RS 21n
The name of an alias to be removed.
.RE

.sp
.ne 2
.na
\fB\fIalias-name\fR\fB=\fR\fIstring\fR\fR
.ad
.RS 21n
Assign the value of \fIstring\fR to the alias \fIalias-name\fR.
.RE

.sp
.LP
If no operands are specified, all alias definitions are written to standard
output.
.SH OUTPUT
.sp
.LP
The format for displaying aliases (when no operands or only \fIname\fR operands
are specified) is:
.sp
.in +2
.nf
"%s=%s\en" \fIname\fR, \fIvalue\fR
.fi
.in -2
.sp

.sp
.LP
The \fIvalue\fR string is written with appropriate quoting so that it is
suitable for reinput to the shell.
.SH EXAMPLES
.LP
\fBExample 1 \fRModifying a Command's Output
.sp
.LP
This example specifies that the output of the \fBls\fR utility is columnated
and more annotated:

.sp
.in +2
.nf
example% \fBalias ls="ls \(miCF"\fR
.fi
.in -2
.sp

.LP
\fBExample 2 \fRRepeating Previous Entries in the Command History File
.sp
.LP
This example creates a simple "redo" command to repeat previous entries in the
command history file:

.sp
.in +2
.nf
example% \fBalias r='fc \(mis'\fR
.fi
.in -2
.sp

.LP
\fBExample 3 \fRSpecifying a Command's Output Options
.sp
.LP
This example provides that the \fBdu\fR utility summarize disk output in units
of 1024 bytes:

.sp
.in +2
.nf
example% \fBalias du=du \(mik\fR
.fi
.in -2
.sp

.LP
\fBExample 4 \fRDealing with an Argument That is an Alias Name
.sp
.LP
This example sets up the \fBnohup\fR utility so that it can deal with an
argument that is an alias name:

.sp
.in +2
.nf
example% \fBalias nohup="nohup "\fR
.fi
.in -2
.sp

.SH ENVIRONMENT VARIABLES
.sp
.LP
See \fBenviron\fR(7) for descriptions of the following environment variables
that affect the execution of \fBalias\fR and \fBunalias\fR: \fBLANG\fR,
\fBLC_ALL\fR, \fBLC_CTYPE\fR, \fBLC_MESSAGES\fR, and \fBNLSPATH\fR.
.SH EXIT STATUS
.sp
.LP
The following exit values are returned:
.sp
.ne 2
.na
\fB\fB0\fR\fR
.ad
.RS 5n
Successful completion.
.RE

.SS "\fBalias\fR"
.sp
.ne 2
.na
\fB\fB>0\fR\fR
.ad
.RS 6n
One of the \fIalias-name\fR operands specified did not have an alias
definition, or an error occurred.
.RE

.SS "\fBunalias\fR"
.sp
.ne 2
.na
\fB\fB>0\fR\fR
.ad
.RS 6n
One of the \fIalias-name\fR operands specified did not represent a valid alias
definition, or an error occurred.
.RE

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.SS "\fBcsh, ksh\fR"
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Committed
_
Standard	See \fBstandards\fR(7).
.TE

.SS "\fBksh93\fR"
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Uncommitted
.TE

.SH SEE ALSO
.sp
.LP
.BR csh (1),
.BR ksh (1),
.BR ksh93 (1),
.BR shell_builtins (1),
.BR attributes (7),
.BR environ (7),
.BR standards (7)