Permissions
d
groups command you can also use id -Gn
chmod
ugoa User category user, group,other ,all
rwx Read Write Execute
UGO
Commonly Used Permissions
chgrp changes the group
umask [-S] [mode]
Common unmask modes
022
002
077
007
Umask permutation
umask 0022 is the same as umask 022
chmod 06400 is the same as chmod 644