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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 (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 permis-
       sion bits in the mode argument supplied during calls to  the  following
       functions:
        *  open(),  openat(), creat(), mkdir(), mkdirat(), mkfifo(), and mkfi-
           foat()
        *  mknod(), mknodat()
        *  mq_open()
        *  sem_open()
       Bit positions that are set in cmask are cleared in the mode of the cre-
       ated 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 unspec-
       ified 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 Electri-
       cal  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.ker-
       nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group                  2013                            UMASK(3P)