Setuid shell files

[utzoo!decvax!ucbvax!unix-wizards]

>From THOMAS at UTAH-20 Thu Aug 13 08:45:13 1981
I recall somebody at the San Francisco conference talking about a hack
somebody (Dennis Ritchie?) had proposed to get around the problem of
having two shells coexisting on one system.  The idea was that a shell
file would specify the name of the interpreter on the first line:
#! /bin/sh
The kernel would recognize this and exec /bin/sh with the shell script
as its first argument.  Once you have the kernel doing this, it's easy
to make the suid bit work.  The reason it can't be done now, of course,
is that there is no way for your shell to do a setuid() call.  Anybody
worked on this?  
=S
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