umask - set file creation mode mask
umask EXPR
umask
Sets the umask for the process to EXPR and returns the previous value. If EXPR is omitted, merely returns the current umask.
If umask(2)
is not implemented on your system and you are
trying to restrict access for yourself (i.e.,
(EXPR & 0700) > 0), produces a fatal error at
run time. If umask(2)
is not implemented and you are not
trying to restrict access for yourself, returns undef.
Remember that a umask is a number, usually given in octal; it is not a string of octal digits. See also oct, if all you have is a string.