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.

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.1‐2008, 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.1‐2008, 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.1‐2008, 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.1‐2008, 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, 2013 Edition,
       Standard  for  Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers,  Inc
       and  The  Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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 .