mirror of https://github.com/mkerrisk/man-pages
161 lines
3.8 KiB
Groff
161 lines
3.8 KiB
Groff
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "EXPORT" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" export
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.SH NAME
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export \- set the export attribute for variables
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.SH SYNOPSIS
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.LP
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\fBexport name\fP\fB[\fP\fB=\fP\fIword\fP\fB]\fP\fB...
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.br
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.sp
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export -p
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.br
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\fP
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.SH DESCRIPTION
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.LP
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The shell shall give the \fIexport\fP attribute to the variables corresponding
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to the specified \fIname\fPs, which shall cause
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them to be in the environment of subsequently executed commands. If
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the name of a variable is followed by = \fIword\fP, then the
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value of that variable shall be set to \fIword\fP.
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.LP
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The \fIexport\fP special built-in shall support the Base Definitions
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volume of IEEE\ Std\ 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
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.LP
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When \fB-p\fP is specified, \fIexport\fP shall write to the standard
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output the names and values of all exported variables, in
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the following format:
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.sp
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.RS
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.nf
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\fB"export %s=%s\\n", <\fP\fIname\fP\fB>, <\fP\fIvalue\fP\fB>
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\fP
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.fi
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.RE
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.LP
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if \fIname\fP is set, and:
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.sp
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.RS
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.nf
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\fB"export %s\\n", <\fP\fIname\fP\fB>
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\fP
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.fi
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.RE
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.LP
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if \fIname\fP is unset.
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.LP
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The shell shall format the output, including the proper use of quoting,
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so that it is suitable for reinput to the shell as
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commands that achieve the same exporting results, except:
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.IP " 1." 4
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Read-only variables with values cannot be reset.
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.LP
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.IP " 2." 4
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Variables that were unset at the time they were output need not be
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reset to the unset state if a value is assigned to the
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variable between the time the state was saved and the time at which
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the saved output is reinput to the shell.
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.LP
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.LP
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When no arguments are given, the results are unspecified.
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.SH OPTIONS
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.LP
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See the DESCRIPTION.
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.SH OPERANDS
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.LP
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See the DESCRIPTION.
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.SH STDIN
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.LP
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Not used.
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.SH INPUT FILES
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.LP
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None.
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.SH ENVIRONMENT VARIABLES
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.LP
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None.
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.SH ASYNCHRONOUS EVENTS
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.LP
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Default.
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.SH STDOUT
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.LP
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See the DESCRIPTION.
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.SH STDERR
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.LP
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The standard error shall be used only for diagnostic messages.
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.SH OUTPUT FILES
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.LP
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None.
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.SH EXTENDED DESCRIPTION
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.LP
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None.
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.SH EXIT STATUS
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.LP
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Zero.
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.SH CONSEQUENCES OF ERRORS
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.LP
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Default.
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.LP
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\fIThe following sections are informative.\fP
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.SH APPLICATION USAGE
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.LP
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None.
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.SH EXAMPLES
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.LP
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Export \fIPWD\fP and \fIHOME\fP variables:
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.sp
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.RS
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.nf
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\fBexport PWD HOME
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\fP
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.fi
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.RE
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.LP
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Set and export the \fIPATH\fP variable:
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.sp
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.RS
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.nf
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\fBexport PATH=/local/bin:$PATH
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\fP
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.fi
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.RE
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.LP
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Save and restore all exported variables:
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.sp
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.RS
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.nf
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\fBexport -p >\fP \fItemp-file\fP\fBunset\fP \fIa lot of variables\fP\fB...\fP \fIprocessing\fP\fB.\fP \fItemp-file\fP
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.fi
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.RE
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.SH RATIONALE
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.LP
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Some historical shells use the no-argument case as the functional
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equivalent of what is required here with \fB-p\fP. This
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feature was left unspecified because it is not historical practice
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in all shells, and some scripts may rely on the now-unspecified
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results on their implementations. Attempts to specify the \fB-p\fP
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output as the default case were unsuccessful in achieving
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consensus. The \fB-p\fP option was added to allow portable access
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to the values that can be saved and then later restored using;
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for example, a \fIdot\fP script.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fISpecial Built-In Utilities\fP
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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