explain_putenv_or_die(3) Library Functions Manual explain_putenv_or_die(3)NAME
explain_putenv_or_die - change or add an environment variable and report errors
SYNOPSIS
#include <libexplain/putenv.h>
void explain_putenv_or_die(char *string);
int explain_putenv_on_error(char *string);
DESCRIPTION
The explain_putenv_or_die function is used to call the putenv(3) system call. On failure an explanation will be printed to stderr, obtained
from the explain_putenv(3) function, and then the process terminates by calling exit(EXIT_FAILURE).
The explain_putenv_on_error function is used to call the putenv(3) system call. On failure an explanation will be printed to stderr,
obtained from the explain_putenv(3) function, but still returns to the caller.
string The string, exactly as to be passed to the putenv(3) system call.
RETURN VALUE
The explain_putenv_or_die function only returns on success, see putenv(3) for more information. On failure, prints an explanation and
exits, it does not return.
The explain_putenv_on_error function always returns the value return by the wrapped putenv(3) system call.
EXAMPLE
The explain_putenv_or_die function is intended to be used in a fashion similar to the following example:
explain_putenv_or_die(string);
SEE ALSO putenv(3)
change or add an environment variable
explain_putenv(3)
explain putenv(3) errors
exit(2) terminate the calling process
COPYRIGHT
libexplain version 0.52
Copyright (C) 2010 Peter Miller
explain_putenv_or_die(3)
Check Out this Related Man Page
PUTENV(3) Linux Programmer's Manual PUTENV(3)NAME
putenv - change or add an environment variable
SYNOPSIS
#include <stdlib.h>
int putenv(char *string);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
putenv(): _XOPEN_SOURCE
|| /* Glibc since 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _SVID_SOURCE
DESCRIPTION
The putenv() function adds or changes the value of environment variables. The argument string is of the form name=value. If name does not
already exist in the environment, then string is added to the environment. If name does exist, then the value of name in the environment
is changed to value. The string pointed to by string becomes part of the environment, so altering the string changes the environment.
RETURN VALUE
The putenv() function returns zero on success, or nonzero if an error occurs. In the event of an error, errno is set to indicate the
cause.
ERRORS
ENOMEM Insufficient space to allocate new environment.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
+----------+---------------+---------------------+
|Interface | Attribute | Value |
+----------+---------------+---------------------+
|putenv() | Thread safety | MT-Unsafe const:env |
+----------+---------------+---------------------+
CONFORMING TO
POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.
NOTES
The putenv() function is not required to be reentrant, and the one in glibc 2.0 is not, but the glibc 2.1 version is.
Since version 2.1.2, the glibc implementation conforms to SUSv2: the pointer string given to putenv() is used. In particular, this string
becomes part of the environment; changing it later will change the environment. (Thus, it is an error is to call putenv() with an auto-
matic variable as the argument, then return from the calling function while string is still part of the environment.) However, glibc ver-
sions 2.0 to 2.1.1 differ: a copy of the string is used. On the one hand this causes a memory leak, and on the other hand it violates
SUSv2.
The 4.4BSD version, like glibc 2.0, uses a copy.
SUSv2 removes the const from the prototype, and so does glibc 2.1.3.
SEE ALSO clearenv(3), getenv(3), setenv(3), unsetenv(3), environ(7)COLOPHON
This page is part of release 4.15 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 https://www.kernel.org/doc/man-pages/.
GNU 2016-03-15 PUTENV(3)