|SETENV(3)||Linux Programmer's Manual||SETENV(3)|
NAMEsetenv - change or add an environment variable
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)):
_BSD_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600
DESCRIPTIONThe 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 succeeds, and the environment is unchanged.
RETURN VALUEThe setenv() function returns zero on success, or -1 on error, with errno set to indicate the cause of the error.
- name is NULL, points to a string of length 0, or contains an '=' character.
- Insufficient memory to add a new variable to the environment.
CONFORMING TO4.3BSD, POSIX.1-2001.
NOTESPOSIX.1-2001 does not require setenv() or unsetenv() to be reentrant.
BUGSPOSIX.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 ALSOclearenv(3), getenv(3), putenv(3), environ(7)
COLOPHONThis 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/.