EXPORT(1)                  POSIX Programmer's Manual                 EXPORT(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
       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 SS
       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 .



IEEE/The Open Group                  2017                            EXPORT(1)
