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 Alias
       Substitution . The aliases shall be removed from the current shell execution  environment;
       see Shell Execution Environment .

OPTIONS

       The  unalias utility shall conform to the Base Definitions volume of IEEE Std 1003.1-2001,
       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  IEEE Std 1003.1-2001, 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 IEEE Std 1003.1-2001,
       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

       Shell Command Language , alias

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2003  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  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 .