PUTENV(3C)                           SysV                           PUTENV(3C)



NAME
     putenv - change or add value to environment

SYNOPSIS
     #include <stdlib.h>

     int putenv (string)
     char *string;

DESCRIPTION
     The putenv function sets the value of an environment variable by altering
     an existing variable or by creating a new one.  The string argument
     points to a string of the form name=value, where name is the environment
     variable and value is the new value for it.

     string points to a string of the form ``name=value.''  The string pointed
     to by string becomes part of the environment, so altering the string will
     change the environment.  The space used by string is no longer used once
     a new string-defining name is passed to putenv.

SEE ALSO
     exec(2), getenv(3C), malloc(3C), clearenv(3C),environ(5).

DIAGNOSTICS
     putenv returns nonzero if it was unable to obtain enough space via malloc
     for an expanded environment, otherwise zero.

WARNINGS
     putenv manipulates the environment pointed to by environ, and can be used
     in conjunction with getenv.  However, envp (the third argument to main)
     is not changed.
     This routine uses malloc(3C) to enlarge the environment.
     After putenv is called, environmental variables are not in alphabetical
     order.
     A potential error is to call putenv with an automatic variable as the
     argument, then exit the calling function while string is still part of
     the environment.