Provided by: manpages-dev_2.17-1_all
umask - set file mode creation mask
mode_t umask(mode_t mask);
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) (so, for example, the
common umask default value of 022 results in new files being created
with permissions 0666 & ~022 = 0644 = rw-r--r-- in the usual case where
the mode is specified to open(2) as 0666).
This system call always succeeds and the previous value of the mask is
SVr4, SVID, POSIX, X/OPEN, 4.3BSD
chmod(2), mkdir(2), open(2)