NAME
setenv - change or add an environment variable
SYNOPSIS
#include <stdlib.h>
I int setenv(const char * name , const char * value , int overwrite );
I int unsetenv(const char * name );
DESCRIPTION
The
R setenv ()
function adds the variable name to the
environment with the value value, if name does not
already exist.
If name does exist in the environment, then
its value is changed to value if overwrite is non-zero;
if overwrite is zero, then the value of name is not
changed.
The
R unsetenv ()
function deletes the variable name from
the environment.
RETURN VALUE
The
R setenv ()
function returns zero on success, or -1 if there
was insufficient space in the environment.
The
R unsetenv ()
function returns zero on success,
or -1 on error, with
errno
set to indicate the cause of the error.
ERRORS
EINVAL
name
contained an '=' character.
CONFORMING TO
4.3BSD, POSIX.1-2001.
NOTES
Prior to glibc 2.2.2,
R unsetenv ()
was prototyped
as returning void; more recent glibc versions follow the
POSIX.1-2001-compliant prototype shown in the SYNOPSIS.
BUGS
POSIX.1-2001 specifies that if
name
contains an '=' character, then
R setenv ()
should fail with the error
R EINVAL ;
however, versions of glibc before 2.3.4 allowed an '=' sign in
R name .
SEE ALSO
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