umask(3p) — Linux manual page


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

       umask — set and get the file mode creation mask

SYNOPSIS         top

       #include <sys/stat.h>

       mode_t umask(mode_t cmask);

DESCRIPTION         top

       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

        *  mknod(), mknodat()

        *  mq_open()

        *  sem_open()

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

RETURN VALUE         top

       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         top

       No errors are defined.

       The following sections are informative.

EXAMPLES         top




RATIONALE         top

       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.1‐2017.



SEE ALSO         top

       creat(3p), exec(1p), mkdir(3p), mkfifo(3p), mknod(3p),
       mq_open(3p), open(3p), sem_open(3p)

       The Base Definitions volume of POSIX.1‐2017, sys_stat.h(0p),

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  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 .

       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 .

IEEE/The Open Group               2017                         UMASK(3P)

Pages that refer to this page: sys_stat.h(0p)mkdir(1p)sh(1p)umask(1p)exec(3p)mkdir(3p)mkfifo(3p)mknod(3p)open(3p)posix_typed_mem_open(3p)shm_open(3p)