Alternate Shells

[Ken Arnold%CGL]

>>From: conor at Glacier.ARPA (Conor Rafferty)
>>Subject: Alternate Shells
>>Summary: Why is chsh fascist?
>
>>A quickie: 4.2BSD chsh does not allow the user to specify alternative
>>shells - only "sh" and "csh" are permitted. Why is this? It seems
>>ironically inappropriate in UNIX, where the shell is ``an ordinary,
>>swappable user program'' and ``user-selectable system interfaces [...]
>>become essentially trivial to implement'' [Ritchie & Thompson CACM 1974].
>
>One obvious reason probably had more to do with the 'nuisance' of people
>setting various things to be their shell and then finding out it was a
>bad choice...

I helped make this decision -- it was because people who left their
terminals unattended for a few minutes (to relieve themselves, say)
would find themselves with a strange shell the next time they logged
on.  This kind of prank became such a pain (besides being virtually
unfixable without finding a super-user, a species of (alleged) person
not always available when you have an assigment due the next morning)
that we decided to turn off chsh to non-normal shells except for root.

		Ken Arnold