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Special Usage (overloading) of Permission Bits on various Unix flavours

apart from read/write/execute. So it's about:

S_ISUID   04000 set user ID on execution
S_ISGID   02000 set group ID on execution
S_ISVTX   01000 sticky bit
See also chmod(2).

The sticky bit in /tmp is well known. But then I heard of more special meanings and became curious.

By the way: did you know that the setuid bit is patented? Pt. no 4135240. Fortunately, by Dennis M. Ritchie himself.
See f.i. the USPTO search and search for this number. Update: see google patents/US4135240.

2015-05-01 (see recent changes)


1. Files

set uid (without execute by user)

set gid (without execute by group)

sticky bit


2. Directories

set uid

set gid

sticky bit


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