PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

UNSETENV(3P)              POSIX Programmer's Manual             UNSETENV(3P)

PROLOG         top

       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.

NAME         top

       unsetenv — remove an environment variable

SYNOPSIS         top

       #include <stdlib.h>

       int unsetenv(const char *name);

DESCRIPTION         top

       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.

RETURN VALUE         top

       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         top

       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         top

       None.

APPLICATION USAGE         top

       None.

RATIONALE         top

       Refer to the RATIONALE section in setenv(3p).

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       getenv(3p), setenv(3p)

       The Base Definitions volume of POSIX.1‐2008, stdlib.h(0p),
       sys_types.h(0p)

COPYRIGHT         top

       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)