umask

UMASK(3POSIX)               POSIX Programmer's Manual              UMASK(3POSIX)



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.


NAME
       umask — set and get the file mode creation mask

SYNOPSIS
       #include <sys/stat.h>

       mode_t umask(mode_t cmask);

DESCRIPTION
       The umask() function shall set the file mode creation mask of the process
       to cmask and return the previous value of the mask. Only the file
       permission bits of cmask (see <sys/stat.h>) are used; the meaning of the
       other bits is implementation-defined.

       The file mode creation mask of the process is used to turn off permission
       bits in the mode argument supplied during calls to the following
       functions:

        *  open(), openat(), creat(), mkdir(), mkdirat(), mkfifo(), and
           mkfifoat()

        *  mknod(), mknodat()

        *  mq_open()

        *  sem_open()

       Bit positions that are set in cmask are cleared in the mode of the
       created file.

RETURN VALUE
       The file permission bits in the value returned by umask() shall be the
       previous value of the file mode creation mask. The state of any other
       bits in that value is unspecified, except that a subsequent call to
       umask() with the returned value as cmask shall leave the state of the
       mask the same as its state before the first call, including any
       unspecified use of those bits.

ERRORS
       No errors are defined.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       Unsigned argument and return types for umask() were proposed. The return
       type and the argument were both changed to mode_t.

       Historical implementations have made use of additional bits in cmask for
       their implementation-defined purposes. The addition of the text that the
       meaning of other bits of the field is implementation-defined permits
       these implementations to conform to this volume of POSIX.1‐2008.

FUTURE DIRECTIONS
       None.

SEE ALSO
       creat(), exec, mkdir(), mkfifo(), mknod(), mq_open(), open(), sem_open()

       The Base Definitions volume of POSIX.1‐2008, <sys_stat.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 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                         UMASK(3POSIX)