AT&T UNIX™PC Unix System V Users Manual - tenox

PUTENV (3C) PUTENV (3C)
NAME
putenv - change or add value to environment
SYNOPSIS
int putenv (string)
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.
SEE ALSO
exec(2), getenv(3C), malloc(3C), environ(S).
DIAGNOSTICS
Putenv returns non-zero 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.
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