PUTENV(3C) (C Programming Language Utilities) 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(5).
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.
Page 1 May 1989