getenv, secure_getenv — get an environment variable
||const char *name
||const char *name
searches the environment list to find the environment
returns a pointer to the corresponding
secure_getenv() function is just like
getenv() except that it returns
NULL in cases where "secure execution" is required. Secure
execution is required if one of the following conditions was
true when the program run by the calling process was
the process's effective user ID did not match its real user ID or the process's effective group ID did not match its real group ID (typically this is the result of executing a set-user-ID or set-group-ID program);
the effective capability bit was set on the executable file; or
the process has a nonempty permitted capability set.
Secure execution may also required if triggered by some Linux security modules.
is intended for use in general-purpose libraries to avoid
vulnerabilities that could occur if set-user-ID or
set-group-ID programs accidentally trusted the
returns a pointer to the value in the environment, or NULL if
there is no match.
For an explanation of the terms used in this section, see attributes(7).
||Thread safety||MT-Safe env|
POSIX.1-2008, C89, C99, SVr4, 4.3BSD.
secure_getenv() is a GNU
The strings in the environment list are of the form
As typically implemented,
getenv() returns a pointer to a string
within the environment list. The caller must take care not to
modify this string, since that would change the environment
of the process.
The implementation of
getenv() is not required to be reentrant.
The string pointed to by the return value of
getenv() may be statically allocated, and
can be modified by a subsequent call to
getenv(), putenv(3), setenv(3), or unsetenv(3).
The "secure execution" mode of
secure_getenv() is controlled by the
AT_SECURE flag contained in the
auxiliary vector passed from the kernel to user space.
This page is part of release 4.07 of the Linux
man-pages project. A
description of the project, information about reporting bugs,
and the latest version of this page, can be found at
Copyright 1993 David Metcalfe (davidprism.demon.co.uk)
and Copyright (C) 2007, 2012 Michael Kerrisk <mtk.manpagesgmail.com>
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Linux libc source code
Lewine's "POSIX Programmer's Guide" (O'Reilly & Associates, 1991)
386BSD man pages
Modified Sat Jul 24 19:30:29 1993 by Rik Faith (faithcs.unc.edu)
Modified Fri Feb 14 21:47:50 1997 by Andries Brouwer (aebcwi.nl)