+@cmd{PERMISSIONS} changes the permissions of a file.
+There is one mandatory subcommand which specifies the permissions to
+which the file should be changed.
+If you set a file's permission to READONLY, then the file will become
+unwritable either by you or anyone else on the system.
+If you set the permission to WRITEABLE, then the file will become
+writeable by you; the permissions afforded to others will be
+unchanged.
+This command cannot be used if the SAFER setting is active.