PUTENV(S) UNIX System V PUTENV(S)
Name
putenv - change or add value to environment
Syntax
int putenv (string)
char *string;
Description
string points to a string of the form ``name=value.'' The
putenv function 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(S), getenv(S), malloc(S), environ(M)
Diagnostics
The putenv function returns non-zero if it was unable to
obtain enough space via malloc for an expanded environment,
otherwise zero.
Warnings
The putenv function 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.
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.
This routine uses malloc(S) to enlarge the environment.
Standards Conformance
putenv is conformant with:
AT&T SVID Issue 2, Select Code 307-127;
and The X/Open Portability Guide II of January 1987.
(printed 6/20/89)