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UMASK(2) FreeBSD System Calls Manual UMASK(2)
NAME
umask - set file creation mode mask
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/stat.h>
mode_t
umask(mode_t numask);
DESCRIPTION
The umask() routine sets the process's file mode creation mask to numask
and returns the previous value of the mask. The 9 low-order access
permission bits of numask are used by system calls, including open(2),
mkdir(2), and mkfifo(2), to turn off corresponding bits requested in file
mode. (See chmod(2)). This clearing allows each user to restrict the
default access to his files.
The default mask value is S_IWGRP|S_IWOTH (022, write access for the
owner only). Child processes inherit the mask of the calling process.
RETURN VALUES
The previous value of the file mode mask is returned by the call.
ERRORS
The umask() system call is always successful.
SEE ALSO
chmod(2), mkfifo(2), mknod(2), open(2)
STANDARDS
The umask() system call is expected to conform to IEEE Std 1003.1-1990
("POSIX.1").
HISTORY
The umask() function appeared in Version 7 AT&T UNIX.
FreeBSD 14.0-RELEASE-p6 June 4, 1993 FreeBSD 14.0-RELEASE-p6