'\" et
.TH UNALIAS "1P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
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.
.\"
.SH NAME
unalias
\(em remove alias definitions
.SH SYNOPSIS
.LP
.nf
unalias \fIalias-name\fR...
.P
unalias -a
.fi
.SH DESCRIPTION
The
.IR unalias
utility shall remove the definition for each alias name specified. See
.IR "Section 2.3.1" ", " "Alias Substitution".
The aliases shall be removed from the current shell execution
environment; see
.IR "Section 2.12" ", " "Shell Execution Environment".
.SH OPTIONS
The
.IR unalias
utility shall conform to the Base Definitions volume of POSIX.1\(hy2017,
.IR "Section 12.2" ", " "Utility Syntax Guidelines".
.P
The following option shall be supported:
.IP "\fB\-a\fP" 10
Remove all alias definitions from the current shell execution
environment.
.SH OPERANDS
The following operand shall be supported:
.IP "\fIalias-name\fR" 10
The name of an alias to be removed.
.SH STDIN
Not used.
.SH "INPUT FILES"
None.
.SH "ENVIRONMENT VARIABLES"
The following environment variables shall affect the execution of
.IR unalias :
.IP "\fILANG\fP" 10
Provide a default value for the internationalization variables that are
unset or null. (See the Base Definitions volume of POSIX.1\(hy2017,
.IR "Section 8.2" ", " "Internationalization Variables"
for the precedence of internationalization variables used to determine
the values of locale categories.)
.IP "\fILC_ALL\fP" 10
If set to a non-empty string value, override the values of all the
other internationalization variables.
.IP "\fILC_CTYPE\fP" 10
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).
.IP "\fILC_MESSAGES\fP" 10
.br
Determine the locale that should be used to affect the format and
contents of diagnostic messages written to standard error.
.IP "\fINLSPATH\fP" 10
Determine the location of message catalogs for the processing of
.IR LC_MESSAGES .
.SH "ASYNCHRONOUS EVENTS"
Default.
.SH STDOUT
Not used.
.SH STDERR
The standard error shall be used only for diagnostic messages.
.SH "OUTPUT FILES"
None.
.SH "EXTENDED DESCRIPTION"
None.
.SH "EXIT STATUS"
The following exit values shall be returned:
.IP "\00" 6
Successful completion.
.IP >0 6
One of the
.IR alias-name
operands specified did not represent a valid alias definition, or an
error occurred.
.SH "CONSEQUENCES OF ERRORS"
Default.
.LP
.IR "The following sections are informative."
.SH "APPLICATION USAGE"
Since
.IR unalias
affects the current shell execution environment, it is generally
provided as a shell regular built-in.
.SH EXAMPLES
None.
.SH RATIONALE
The
.IR unalias
description is based on that from 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\(hy2017, such as command line editing.
.P
The
.BR \-a
option is the equivalent of the
.IR unalias
* form of the C shell and is provided to address security concerns
about unknown aliases entering the environment of a user (or
application) through the allowable implementation-defined predefined
alias route or as a result of an
.IR ENV
file. (Although
.IR unalias
could be used to simplify the ``secure'' shell script shown in the
.IR command
rationale, it does not obviate the need to quote all command names. An
initial call to
.IR unalias
.BR \-a
would have to be quoted in case there was an alias for
.IR unalias .)
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "Chapter 2" ", " "Shell Command Language",
.IR "\fIalias\fR\^"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "Chapter 8" ", " "Environment Variables",
.IR "Section 12.2" ", " "Utility Syntax Guidelines"
.\"
.SH 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 .
.PP
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 .