umask(2)umask(2)NAMEumask - Sets and gets the value of the file creation mask
SYNOPSIS
#include <sys/types.h> #include <sys/stat.h>
mode_t umask(
mode_t cmask );
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
umask(): POSIX.1, XSH4.0, XSH4.2, XSH5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
Specifies the value of the file mode creation mask.
DESCRIPTION
The umask() function sets the file mode creation mask of the process to
the value of the cmask parameter and returns the previous value of the
mask. The cmask parameter is constructed by a logical OR operation on
the file permission bits defined in the <sys/mode.h> header file.
Whenever a file is created (by the open(), mkdir(), mkfifo(), or
mknod() function), all file permission bits set in the file mode cre‐
ation mask are cleared in the mode of the created file. This clearing
lets users restrict the default access to their files.
The mask is inherited by child processes.
RETURN VALUES
Upon successful completion, the previous value of the file mode cre‐
ation mask is returned. The state of any other bits in that value is
unspecified, except that a subsequent call to umask() with the returned
value as cmask will leave the mask in the same as its state before the
first call, including any unspecified use of those bits.
ERRORS
No errors are defined.
SEE ALSO
Commands: chmod(1), mkdir(1), Bourne shell sh(1b), POSIX shell sh(1p),
umask(1)
Functions: chmod(2), mkdir(2), mknod(2), open(2), stat(2)
Standards: standards(5)umask(2)
