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       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

       export — set the export attribute for variables

SYNOPSIS

       export name[=word]...

       export -p

DESCRIPTION

       The  shell shall give the export attribute to the variables corresponding to the specified
       names, which shall cause them to be in the environment of subsequently executed  commands.
       If  the  name of a variable is followed by =word, then the value of that variable shall be
       set to word.

       The export special built-in shall support the Base  Definitions  volume  of  POSIX.1‐2017,
       Section 12.2, Utility Syntax Guidelines.

       When  -p  is  specified, export shall write to the standard output the names and values of
       all exported variables, in the following format:

           "export %s=%s\n", <name>, <value>

       if name is set, and:

           "export %s\n", <name>

       if name is unset.

       The shell shall format the output, including the proper use of  quoting,  so  that  it  is
       suitable  for  reinput  to  the shell as commands that achieve the same exporting results,
       except:

        1. Read-only variables with values cannot be reset.

        2. Variables that were unset at the time they were output need not be reset to the  unset
           state  if a value is assigned to the variable between the time the state was saved and
           the time at which the saved output is reinput to the shell.

       When no arguments are given, the results are unspecified.

OPTIONS

       See the DESCRIPTION.

OPERANDS

       See the DESCRIPTION.

STDIN

       Not used.

INPUT FILES

       None.

ENVIRONMENT VARIABLES

       None.

ASYNCHRONOUS EVENTS

       Default.

STDOUT

       See the DESCRIPTION.

STDERR S

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES

       None.

EXTENDED DESCRIPTION

       None.

EXIT STATUS

        0    All name operands were successfully exported.

       >0    At least one name could not be exported, or the -p option was specified and an error
             occurred.

CONSEQUENCES OF ERRORS

       Default.

       The following sections are informative.

APPLICATION USAGE

       Note that, unless X was previously marked readonly, the value of "$?" after:

           export X=$(false)

       will  be  0  (because  export  successfully  set X to the empty string) and that execution
       continues, even if set -e is in effect. In order to detect command substitution  failures,
       a user must separate the assignment from the export, as in:

           X=$(false)
           export X

EXAMPLES

       Export PWD and HOME variables:

           export PWD HOME

       Set and export the PATH variable:

           export PATH=/local/bin:$PATH

       Save and restore all exported variables:

           export -p > temp-file
           unset a lot of variables
           ... processing
           . temp-file

RATIONALE

       Some  historical  shells  use the no-argument case as the functional equivalent of what is
       required here with -p.  This feature was left unspecified because  it  is  not  historical
       practice  in all shells, and some scripts may rely on the now-unspecified results on their
       implementations. Attempts to specify the -p output as the default case  were  unsuccessful
       in  achieving  consensus.   The -p option was added to allow portable access to the values
       that can be saved and then later restored using; for example, a dot script.

FUTURE DIRECTIONS

       None.

SEE ALSO

       Section 2.14, Special Built-In Utilities

       The Base Definitions volume of POSIX.1‐2017, 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 .