Name
umask — set file mode creation mask
Synopsis
mode_t umask( |
mode_t |
mask) ; |
DESCRIPTION
umask
() sets the calling
process's file mode creation mask (umask) to mask
& 0777.
The umask is used by open(2), mkdir(2), and other system
calls that create files to modify the permissions placed on
newly created files or directories. Specifically, permissions
in the umask are turned off from the mode
argument to open(2) and mkdir(2).
The constants that should be used to specify mask
are described under
stat(2).
The typical default value for the process umask is
S_IWGRP | S_IWOTH
(octal 022). In the usual case where the mode
argument to open(2) is specified
as:
(octal 0666) when creating a new file, the permissions on
the resulting file will be:
(because 0666 & ~022 = 0644; i.e., rw-r--r--).
RETURN VALUE
This system call always succeeds and the previous value of
the mask is returned.
CONFORMING TO
SVr4, 4.3BSD, POSIX.1-2001.
NOTES
A child process created via fork(2) inherits its
parent's umask. The umask is left unchanged by execve(2).
SEE ALSO
chmod(2), mkdir(2), open(2), stat(2)
Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
and Copyright (c) 2006, Michael Kerrisk (mtk-manpages@gmx.net)
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Modified by Michael Haardt <michael@moria.de>
Modified Sat Jul 24 12:51:53 1993 by Rik Faith <faith@cs.unc.edu>
Modified Tue Oct 22 22:39:04 1996 by Eric S. Raymond <esr@thyrsus.com>
Modified Thu May 1 06:05:54 UTC 1997 by Nicolás Lichtmaier
<nick@debian.com> with Lars Wirzenius <liw@iki.fi> suggestion
2006-05-13, mtk, substantial rewrite of description of 'mask'
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