from small one page howto to huge articles all in one place
 

search text in:





Poll
What does your sytem tell when running "ulimit -u"?








poll results

Last additions:
using iotop to find disk usage hogs

using iotop to find disk usage hogs

words:

887

views:

85664

userrating:

average rating: 1.7 (82 votes) (1=very good 6=terrible)


May 25th. 2007:
Words

486

Views

202104

why adblockers are bad


Workaround and fixes for the current Core Dump Handling vulnerability affected kernels

Workaround and fixes for the current Core Dump Handling vulnerability affected kernels

words:

161

views:

84125

userrating:

average rating: 1.3 (27 votes) (1=very good 6=terrible)


April, 26th. 2006:

Druckversion
You are here: manpages





GETENV

Section: Linux Programmer's Manual (3)
Updated: 2015-03-02
Index Return to Main Contents
 

NAME

getenv, secure_getenv - get an environment variable  

SYNOPSIS

#include <stdlib.h>

char *getenv(const char *name);

char *secure_getenv(const char *name);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

secure_getenv(): _GNU_SOURCE  

DESCRIPTION

The getenv() function searches the environment list to find the environment variable name, and returns a pointer to the corresponding value string.

The GNU-specific 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 loaded:

*
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.

The secure_getenv() function 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 environment.  

RETURN VALUE

The getenv() function returns a pointer to the value in the environment, or NULL if there is no match.  

VERSIONS

secure_getenv() first appeared in glibc 2.17.  

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
getenv(), secure_getenv() Thread safetyMT-Safe env
 

CONFORMING TO

getenv(): SVr4, POSIX.1-2001, 4.3BSD, C89, C99.

secure_getenv() is a GNU extension.  

NOTES

The strings in the environment list are of the form name=value.

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.  

SEE ALSO

clearenv(3), getauxval(3), putenv(3), setenv(3), unsetenv(3), capabilities(7), environ(7)  

COLOPHON

This page is part of release 3.81 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 http://www.kernel.org/doc/man-pages/.


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
VERSIONS
ATTRIBUTES
CONFORMING TO
NOTES
SEE ALSO
COLOPHON


Please read "Why adblockers are bad".



Other free services
toURL.org
Shorten long
URLs to short
links like
http://tourl.org/2
tourl.org
.
Reverse DNS lookup
Find out which hostname(s)
resolve to a
given IP or other hostnames for the server
www.reversednslookup.org
rdf newsfeed | rss newsfeed | Atom newsfeed
- Powered by LeopardCMS - Running on Gentoo -
Copyright 2004-2013 Sascha Nitsch Unternehmensberatung UG(haftungsbeschränkt)
Valid XHTML1.1 : Valid CSS : buttonmaker
- Level Triple-A Conformance to Web Content Accessibility Guidelines 1.0 -
- Copyright and legal notices -
Time to create this page: 3.3 ms