putenv.3c (2010 09)

p
putenv(3C) putenv(3C)
NAME
putenv( ) - change or add value to environment
SYNOPSIS
#include <stdlib.h>
int putenv(const char *string);
DESCRIPTION
string points to a string of the form name=value.
putenv() makes the value of the environment vari-
able 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 changes the environment.
The space used by string is no longer used once a new string-defining name is passed to
putenv().
EXTERNAL INFLUENCES
Locale
The
LC_CTYPE category determines the interpretation of characters in string as single- and/or multi-
byte characters.
International Code Set Support
Single- and multi-byte character code sets are supported.
DIAGNOSTICS
putenv() returns non-zero if it was unable to obtain enough space via malloc() for an expanded
environment, or if an invalid multibyte character sequence was encountered in the string argument; oth-
erwise it returns zero.
ERRORS
putenv() fails under the following conditions:
[ENOMEM] There is insufficient space to expand the environment.
[EILSEQ] An invalid multibyte character sequence was encountered in the string argument.
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() to enlarge the environment (see malloc (3C)).
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.
SEE ALSO
exec(2), getenv(3C), malloc(3C), environ(5), thread_safety(5).
STANDARDS CONFORMANCE
putenv(): AES, SVID2, SVID3, XPG2, XPG3, XPG4
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1