UMASK(1)
NAME
umask − set file-creation mode mask
SYNOPSIS
umask [ ooo ]
DESCRIPTION
The user file-creation mode mask is set to ooo. The octal three digits refer to read/write/execute permissions for owner, group, and others, respectively (see chmod(2) and umask(2)). The value of each specified digit is subtracted from the corresponding “digit” specified by the system for the creation of a file (see creat(2)). For example, umask 022 removes group and others write permission (files normally created with mode 777 become mode 755; files created created with mode 666 become mode 644).
If ooo is omitted, the current value of the mask is printed.
Umask is recognized and executed by the shell.