UNSETENV(3P) POSIX Programmer's Manual UNSETENV(3P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
NAMEunsetenv — remove an environment variable
SYNOPSIS
#include <stdlib.h>
int unsetenv(const char *name);
DESCRIPTION
The unsetenv() function shall remove an environment variable from the
environment of the calling process. The name argument points to a
string, which is the name of the variable to be removed. The named
argument shall not contain an '=' character. If the named variable does
not exist in the current environment, the environment shall be
unchanged and the function is considered to have completed success‐
fully.
The unsetenv() function shall update the list of pointers to which env‐
iron points.
The unsetenv() function need not be thread-safe.
RETURN VALUE
Upon successful completion, zero shall be returned. Otherwise, −1 shall
be returned, errno set to indicate the error, and the environment shall
be unchanged.
ERRORS
The unsetenv() function shall fail if:
EINVAL The name argument points to an empty string, or points to a
string containing an '=' character.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
None.
RATIONALE
Refer to the RATIONALE section in setenv().
FUTURE DIRECTIONS
None.
SEE ALSOgetenv(), setenv()
The Base Definitions volume of POSIX.1‐2008, <stdlib.h>, <sys_types.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the source
files to man page format. To report such errors, see https://www.ker‐
nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 UNSETENV(3P)
