mirror of https://github.com/mkerrisk/man-pages
83 lines
2.6 KiB
Groff
83 lines
2.6 KiB
Groff
.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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.\" and Copyright (C) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" References consulted:
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.\" Linux libc source code
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.\" Lewine's "POSIX Programmer's Guide" (O'Reilly & Associates, 1991)
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.\" 386BSD man pages
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.\" Modified Sat Jul 24 19:30:29 1993 by Rik Faith (faith@cs.unc.edu)
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.\" Modified Fri Feb 14 21:47:50 1997 by Andries Brouwer (aeb@cwi.nl)
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.\"
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.TH GETENV 3 2008-03-17 "GNU" "Linux Programmer's Manual"
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.SH NAME
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getenv \- get an environment variable
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.SH SYNOPSIS
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.nf
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.B #include <stdlib.h>
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.sp
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.BI "char *getenv(const char *" name );
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.fi
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.SH DESCRIPTION
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The
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.BR getenv ()
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function searches the environment list to find the
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environment variable
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.IR name ,
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and returns a pointer to the corresponding
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.I value
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string.
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.SH "RETURN VALUE"
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The
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.BR getenv ()
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function returns a pointer to the value in the
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environment, or NULL if there is no match.
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.SH "CONFORMING TO"
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SVr4, POSIX.1-2001, 4.3BSD, C89, C99.
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.SH NOTES
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The strings in the environment list are of the form \fIname=value\fP.
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As typically implemented,
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.BR getenv ()
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returns a pointer to a string within the environment list.
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The caller must take care not to modify this string,
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since that would change the environment of the process.
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The implementation of
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.BR getenv ()
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is not required to be reentrant.
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The string pointed to by the return value of
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.BR getenv ()
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may be statically allocated,
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and can be modified by a subsequent call to
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.BR getenv (),
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.BR putenv (3),
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.BR setenv (3),
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or
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.BR unsetenv (3).
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.SH "SEE ALSO"
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.BR clearenv (3),
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.BR putenv (3),
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.BR setenv (3),
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.BR unsetenv (3),
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.BR environ (7)
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