UNALIAS(1)                 POSIX Programmer's Manual                UNALIAS(1)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

NAME
       unalias -- remove alias definitions

SYNOPSIS
       unalias alias-name...

       unalias -a

DESCRIPTION
       The unalias utility shall remove the definition for each alias name
       specified. See Section 2.3.1, Alias Substitution.  The aliases shall be
       removed from the current shell execution environment; see Section 2.12,
       Shell Execution Environment.

OPTIONS
       The unalias utility shall conform to the Base Definitions volume of
       POSIX.1-2017, Section 12.2, Utility Syntax Guidelines.

       The following option shall be supported:

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

OPERANDS
       The following operand shall be supported:

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

STDIN
       Not used.

INPUT FILES
       None.

ENVIRONMENT VARIABLES
       The following environment variables shall affect the execution of
       unalias:

       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.

ASYNCHRONOUS EVENTS
       Default.

STDOUT
       Not used.

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 alias-name operands specified did not represent a
             valid alias definition, or an error occurred.

CONSEQUENCES OF ERRORS
       Default.

       The following sections are informative.

APPLICATION USAGE
       Since unalias affects the current shell execution environment, it is
       generally provided as a shell regular built-in.

EXAMPLES
       None.

RATIONALE
       The 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.1-2017, such as command line
       editing.

       The -a option is the equivalent of the 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 ENV file. (Although unalias could be used to simplify the
       ``secure'' shell script shown in the command rationale, it does not
       obviate the need to quote all command names. An initial call to unalias
       -a would have to be quoted in case there was an alias for unalias.)

FUTURE DIRECTIONS
       None.

SEE ALSO
       Chapter _2, Shell Command Language, alias

       The Base Definitions volume of POSIX.1-2017, Chapter _8, Environment
       Variables, Section 12.2, Utility Syntax Guidelines

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 .

       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                           UNALIAS(1)
