Setuid shell files

[wnj]

The current 4.1bsd system for VAXes includes a mechanism initially
implemented at Bell Labs (after version 7) which allows a file to
be executable and start with a line:
	#! interpreter
where interpreter might be /bin/sh, e.g.
	#! /bin/sh
The file is then a ``true executable'', i.e. an exec() succeeds on
it in the obvious way, and the system interprets setuid and setgid
bits on the file.

	Bill Joy