From: utzoo!decvax!harpo!eagle!mhuxt!mhuxj!cbosgd!mark
Newsgroups: net.unix-wizards
Title: Re: . files, defaults, and generality
Article-I.D.: cbosgd.2759
Posted: Fri Oct 29 11:54:57 1982
Received: Sat Oct 30 05:04:25 1982
Reply-To: mark@cbosgd.UUCP (Mark Horton)
References: microsof.2558

For documentation of the #! feature in Berkeley UNIX, see exec(2).
This is implemented in the kernel, NOT in csh or sh.  This is
probably why it's not documented in csh or sh other than in passing.

This is not a Berkeley convention, by the way, it's a Bell Labs
convention which Berkeley liked and adopted.  (I'm not sure who
at Bell Labs, I think it was the center 127 people who put out
V6 and V7, e.g. Ritchie and Thompson.)  As far as I know, system
III and its descendents (done by different people) have not adopted
this convention.

If you think about how the kernel does execs (with two byte magic
numbers) it should be obvious why #! was chosen.