S_IRUSR S_IREAD Read permission bit for the owner of the file. On many systems this bit is 0400. S_IREAD is an obsolete synonym provided for BSD compatibility.
S_IWUSR S_IWRITE Write permission bit for the owner of the file. Usually 0200. S_IWRITE is an obsolete synonym provided for BSD compatibility.
S_IXUSR S_IEXEC Execute (for ordinary files)orsearch(for directories) permission bit for the owner of the file. Usually 0100. S_IEXEC is an obsolete synonym provided for BSD compatibility.
S_IRWXU This is equivalent to (S_IRUSR | S_IWUSR | S_IXUSR).
S_IRGRP Read permission bit for the group owner of the file. Usually 040.
S_IWGRP Write permission bit for the group owner of the file. Usually 020.
S_IXGRP Execute orsearch permission bit for the group owner of the file. Usually 010.
S_IRWXG This is equivalent to (S_IRGRP | S_IWGRP | S_IXGRP).
S_IROTH Read permission bit for other users. Usually 04.
S_IWOTH Write permission bit for other users. Usually 02.
S_IXOTH Execute orsearch permission bit for other users. Usually 01.
S_IRWXO This is equivalent to (S_IROTH | S_IWOTH | S_IXOTH).
S_ISUID This is the set-user-ID on execute bit, usually 04000. See How Change Persona.
S_ISGID This is the set-group-ID on execute bit, usually 02000. See How Change Persona.