UMASK(P) POSIX Programmer's Manual UMASK(P)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.
NAMEumask - 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 permis‐
sion 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 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
IEEE Std 1003.1-2001.
FUTURE DIRECTIONS
None.
SEE ALSOcreat() , 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, Copyright (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.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 UMASK(P)
