[det]chmod(+File,
+Spec)Set the mode of the target file. Spec is one of +Mode, -Mode
or a plain Mode, which adds new permissions, revokes
permissions or sets the exact permissions. Mode itself is an
integer, a POSIX mode name or a list of POSIX mode names. Defines names
are suid,
sgid, svtx and all names defined by the
regular expression
[ugo]*[rwx]*. Specifying none of "ugo" is the same as
specifying all of them. For example, to make a file executable for the
owner (user) and group, we can use:
?- chmod(myfile, +ugx).
