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setenv(3) [suse man page]

SETENV(3)						     Linux Programmer's Manual							 SETENV(3)

NAME
setenv - change or add an environment variable SYNOPSIS
#include <stdlib.h> int setenv(const char *name, const char *value, int overwrite); int unsetenv(const char *name); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): setenv(), unsetenv(): _BSD_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600 DESCRIPTION
The setenv() function adds the variable name to the environment with the value value, if name does not already exist. If name does exist in the environment, then its value is changed to value if overwrite is nonzero; if overwrite is zero, then the value of name is not changed. This function makes copies of the strings pointed to by name and value (by contrast with putenv(3)). The unsetenv() function deletes the variable name from the environment. If name does not exist in the environment, then the function suc- ceeds, and the environment is unchanged. RETURN VALUE
The setenv() function returns zero on success, or -1 on error, with errno set to indicate the cause of the error. The unsetenv() function returns zero on success, or -1 on error, with errno set to indicate the cause of the error. ERRORS
EINVAL name is NULL, points to a string of length 0, or contains an '=' character. ENOMEM Insufficient memory to add a new variable to the environment. CONFORMING TO
4.3BSD, POSIX.1-2001. NOTES
POSIX.1-2001 does not require setenv() or unsetenv() to be reentrant. Prior to glibc 2.2.2, unsetenv() was prototyped as returning void; more recent glibc versions follow the POSIX.1-2001-compliant prototype shown in the SYNOPSIS. BUGS
POSIX.1-2001 specifies that if name contains an '=' character, then setenv() should fail with the error EINVAL; however, versions of glibc before 2.3.4 allowed an '=' sign in name. SEE ALSO
clearenv(3), getenv(3), putenv(3), environ(7) COLOPHON
This page is part of release 3.25 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. GNU
2009-09-20 SETENV(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(): _SVID_SOURCE || _XOPEN_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. CONFORMING TO
SVr4, POSIX.1-2001, 4.3BSD. NOTES
The putenv() function is not required to be reentrant, and the one in libc4, libc5 and glibc 2.0 is not, but the glibc 2.1 version is. Description for libc4, libc5, glibc: If the argument string is of the form name, and does not contain an '=' character, then the variable name is removed from the environment. If putenv() has to allocate a new array environ, and the previous array was also allocated by putenv(), then it will be freed. In no case will the old storage associated to the environment variable itself be freed. The libc4 and libc5 and glibc 2.1.2 versions conform 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 2.0-2.1.1 differs: a copy of the string is used. On the one hand this causes a memory leak, and on the other hand it violates SUSv2. This has been fixed in glibc 2.1.2. 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 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. GNU
2013-04-19 PUTENV(3)
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