2004-11-03 13:51:07 +00:00
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.\" Hey Emacs! This file is -*- nroff -*- source.
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.\"
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2008-01-09 17:26:35 +00:00
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.\" Copyright (c) 2006, 2008, Michael Kerrisk (mtk.manpages@gmail.com)
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2008-01-09 17:35:14 +00:00
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.\" (A few fragments remain from an earlier (1992) version written in
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2008-01-09 17:26:35 +00:00
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.\" 1992 by Drew Eckhardt <drew@cs.colorado.edu>.)
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2004-11-03 13:51:07 +00:00
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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2007-04-12 22:42:49 +00:00
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.\"
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2004-11-03 13:51:07 +00:00
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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2007-04-12 22:42:49 +00:00
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.\"
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2004-11-03 13:51:07 +00:00
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" Modified by Michael Haardt <michael@moria.de>
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.\" Modified Sat Jul 24 12:51:53 1993 by Rik Faith <faith@cs.unc.edu>
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.\" Modified Tue Oct 22 22:39:04 1996 by Eric S. Raymond <esr@thyrsus.com>
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.\" Modified Thu May 1 06:05:54 UTC 1997 by Nicol<6F>s Lichtmaier
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.\" <nick@debian.com> with Lars Wirzenius <liw@iki.fi> suggestion
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2006-05-12 22:48:55 +00:00
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.\" 2006-05-13, mtk, substantial rewrite of description of 'mask'
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2008-01-09 17:26:35 +00:00
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.\" 2008-01-09, mtk, a few rewrites and additions.
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.TH UMASK 2 2008-01-09 "Linux" "Linux Programmer's Manual"
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2004-11-03 13:51:07 +00:00
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.SH NAME
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2005-06-30 08:07:33 +00:00
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umask \- set file mode creation mask
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.SH SYNOPSIS
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.B #include <sys/types.h>
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.br
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.B #include <sys/stat.h>
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.sp
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.BI "mode_t umask(mode_t " mask );
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.SH DESCRIPTION
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.BR umask ()
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sets the calling process's file mode creation mask (umask) to
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.I mask
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& 0777 (i.e., only the file permission bits of
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.I mask
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are used), and returns the previous value of the mask.
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The umask is used by
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.BR open (2),
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.BR mkdir (2),
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and other system calls that create files
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.\" e.g., mkfifo(), creat(), mknod(), sem_open(), mq_open(), shm_open()
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.\" but NOT the System V IPC *get() calls
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to modify the permissions placed on newly created files or directories.
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Specifically, permissions in the umask are turned off from
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the \fImode\fP argument to
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.BR open (2)
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and
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.BR mkdir (2).
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2007-04-12 22:42:49 +00:00
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The constants that should be used to specify
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.I mask
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are described under
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.BR stat (2).
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The typical default value for the process umask is
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.I S_IWGRP\ |\ S_IWOTH
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(octal 022).
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In the usual case where the
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.I mode
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argument to
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.BR open (2)
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is specified as:
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.nf
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2007-01-04 18:54:52 +00:00
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S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH
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.fi
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(octal 0666) when creating a new file, the permissions on the
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resulting file will be:
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.nf
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S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH
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.fi
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(because 0666 & ~022 = 0644; i.e., rw\-r\-\-r\-\-).
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.SH "RETURN VALUE"
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This system call always succeeds and the previous value of the mask
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is returned.
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2007-05-18 16:30:46 +00:00
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.SH "CONFORMING TO"
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SVr4, 4.3BSD, POSIX.1-2001.
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2006-07-22 14:26:12 +00:00
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.SH NOTES
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A child process created via
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.BR fork (2)
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inherits its parent's umask.
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The umask is left unchanged by
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.BR execve (2).
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The umask setting also affects the permissions assigned to POSIX IPC objects
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.RB ( mq_open (3),
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.BR sem_open (3),
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.BR shm_open (3)),
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FIFOs
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.RB ( mkfifo (3)),
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intro.1, time.1, accept.2, bind.2, connect.2, execve.2, flock.2, getdents.2, getpriority.2, getuid.2, intro.2, ioctl.2, mincore.2, mknod.2, personality.2, ptrace.2, read.2, recv.2, select_tut.2, send.2, sendfile.2, shmctl.2, sigaction.2, signal.2, stat.2, times.2, truncate.2, umask.2, wait.2, MB_CUR_MAX.3, MB_LEN_MAX.3, argz_add.3, btowc.3, clearenv.3, clock.3, cmsg.3, end.3, endian.3, errno.3, exit.3, fgetwc.3, fgetws.3, fopen.3, fputwc.3, fputws.3, fseek.3, fwide.3, getfsent.3, getgrnam.3, gethostid.3, getipnodebyname.3, getmntent.3, getpwnam.3, getwchar.3, grantpt.3, iconv.3, iconv_close.3, iconv_open.3, insque.3, intro.3, iswalnum.3, iswalpha.3, iswblank.3, iswcntrl.3, iswctype.3, iswdigit.3, iswgraph.3, iswlower.3, iswprint.3, iswpunct.3, iswspace.3, iswupper.3, iswxdigit.3, malloc.3, mblen.3, mbrlen.3, mbrtowc.3, mbsinit.3, mbsnrtowcs.3, mbsrtowcs.3, mbstowcs.3, mbtowc.3, mkstemp.3, mktemp.3, nl_langinfo.3, openpty.3, posix_openpt.3, printf.3, ptsname.3, putwchar.3, qecvt.3, rcmd.3, readdir.3, rexec.3, rpc.3, setnetgrent.3, shm_open.3, sigpause.3, stdin.3, stpcpy.3, strftime.3, strptime.3, syslog.3, towctrans.3, towlower.3, towupper.3, ttyslot.3, ungetwc.3, unlocked_stdio.3, wcpcpy.3, wcpncpy.3, wcrtomb.3, wcscasecmp.3, wcscat.3, wcschr.3, wcscmp.3, wcscpy.3, wcscspn.3, wcsdup.3, wcslen.3, wcsncasecmp.3, wcsncat.3, wcsncmp.3, wcsncpy.3, wcsnlen.3, wcsnrtombs.3, wcspbrk.3, wcsrchr.3, wcsrtombs.3, wcsspn.3, wcsstr.3, wcstok.3, wcstombs.3, wcswidth.3, wctob.3, wctomb.3, wctrans.3, wctype.3, wcwidth.3, wmemchr.3, wmemcmp.3, wmemcpy.3, wmemmove.3, wmemset.3, wprintf.3, console_ioctl.4, pts.4, elf.5, filesystems.5, hosts.5, proc.5, ttytype.5, boot.7, capabilities.7, credentials.7, epoll.7, glob.7, koi8-r.7, path_resolution.7, pty.7, signal.7, suffixes.7, time.7, unicode.7, unix.7, uri.7, utf-8.7: global fix: s/Unix/UNIX/
The man pages were rather inconsistent in the use of "Unix"
versus "UNIX". Let's go with the trademark usage.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2010-10-12 04:45:38 +00:00
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and UNIX domain sockets
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2008-01-09 17:26:35 +00:00
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.RB ( unix (7))
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created by the process.
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The umask does not affect the permissions assigned
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to System V IPC objects created by the process (using
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.BR msgget (2),
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.BR semget (2),
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.BR shmget (2)).
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2004-11-03 13:51:07 +00:00
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.SH "SEE ALSO"
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2005-06-30 08:07:33 +00:00
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.BR chmod (2),
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.BR mkdir (2),
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2006-05-12 22:48:55 +00:00
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.BR open (2),
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.BR stat (2)
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2008-01-09 17:26:35 +00:00
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.\" FIXME . eventually: .BR acl (5)
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