The Command Line InterfaceCommand Line AccessCommand Line SecurityDirectories, Permissions, and File OwnershipFile Security and PermissionsSpecial File PermissionsSet User IDSet Group IDSticky BitsHidden File FlagsHow to Modify Permissions and OwnershipUsing chmodUsing chown and chgrpUsing chflagsUsing Get Info to Modify PermissionsCommon UNIX Commandstoppskill and killalllast and whofindnetstatvopensslUNIX SecuritySUID and SGID FilesKernel Security LevelssudoManaging sudo Accesssudo Versus the su CommandSummary