putenv

Syntax

#include <stdlib.h> int putenv(char *env);

Description

This function adds an entry to the program's environment. The string passed must be of the form NAME=VALUE. Any existing value for the environment variable is gone.

putenv will copy the string passed to it, and will automatically free any existing string already in the environment. Keep this in mind if you alter the environment yourself. The string you pass is still your responsibility to free. Note that most implementations will not let you free the string you pass, resulting in memory leaks.

Return Value

Zero on success, nonzero on failure; errno will be set to the relevant error code: currently only ENOMEM (insufficient memory) is possible.

Portability

ANSI/ISO C	No
POSIX	1003.2-1992; 1003.1-2001 (see note 1)

Notes:

1. This function is new to the Posix 1003.1-200x draft

Example

putenv("SHELL=ksh.exe");