NAME

putenv - change or add value to environment

SYNOPSIS

#include <stdlib.h>

int putenv (char *string);

DESCRIPTION

string points to a string of the form ``name=value.'' putenv makes the value of the environment variable name equal to value by altering an existing variable or creating a new one. In either case, 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. Because of this limitation, string should be declared static if it is declared within a function.

SEE ALSO

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

DIAGNOSTICS

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

NOTES

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 the func-
tion putenv with a pointer to an automatic variable  as  the
argument  and to then exit the calling function while string
is still part of the environment.