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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
UNSETENV(3P) POSIX Programmer's Manual UNSETENV(3P)
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.
unsetenv — remove an environment variable
#include <stdlib.h>
int unsetenv(const char *name);
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
successfully.
The unsetenv() function shall update the list of pointers to which
environ points.
The unsetenv() function need not be thread-safe.
Upon successful completion, zero shall be returned. Otherwise, −1
shall be returned, errno set to indicate the error, and the
environment shall be unchanged.
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.
None.
None.
Refer to the RATIONALE section in setenv(3p).
None.
getenv(3p), setenv(3p)
The Base Definitions volume of POSIX.1‐2008, stdlib.h(0p),
sys_types.h(0p)
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 Electrical 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.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 UNSETENV(3P)
Pages that refer to this page: stdlib.h(0p), getenv(3p), setenv(3p)