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



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult 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 process' file mode creation mask 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 process' file mode creation mask is used during open(), creat(), mkdir(), and mkfifo() to turn off permission bits in
       the mode argument supplied. 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 addi-
       tion  of  the text that the meaning of other bits of the field is implementation-defined permits these implementations to
       conform to this volume of IEEE Std 1003.1-2001.

FUTURE DIRECTIONS
       None.

SEE ALSO
       creat(), mkdir(), mkfifo(), open(), the Base Definitions volume of IEEE Std 1003.1-2001, <sys/stat.h>, <sys/types.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003  Edition,  Standard  for
       Information  Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copy-
       right (C) 2001-2003 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   http://www.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                     UMASK(3P)