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From: toby@gargoyle.UChicago.EDU (Toby Harness)
Newsgroups: comp.unix.wizards
Subject: Re: umask under 4.3
Message-ID: <673@gargoyle.UChicago.EDU>
Date: Mon, 1-Jun-87 00:45:30 EDT
Article-I.D.: gargoyle.673
Posted: Mon Jun  1 00:45:30 1987
Date-Received: Tue, 2-Jun-87 06:08:18 EDT
References: <7582@brl-adm.ARPA>
Reply-To: toby@gargoyle.uchicago.edu.UUCP (Toby Harness)
Organization: U. of Chicago, Ogburn/Stouffer Center
Lines: 22

In article <7582@brl-adm.ARPA> bzs@bu-cs.bu.EDU (Barry Shein) suggests:
....
>johndoe::uid:gid:gecos:homedir:/bin/shell
>
>It could be setuid if need be and it would be easy to check argv[0] as
>a hook for which shell to start, /bin/cshell etc. You could re-work
>environment variables before starting the user's shell, limits,
>whatever, even install things like permissible login time windows or
>other security hooks (secondary password, secure ttys etc.) Might have
>to play with chsh but other than that I don't think there would be
>much problem.
>
>There are a number of details, some poorly documented...

Two things to look out for, both involving other programs cranking-up a
sub-shell:  most look at $SHELL, so be sure to reset it to the shell you
are exec'ing; some use the entry in /etc/passwd -- one way around this
would be to check if (ppid() != 1) and skip everything you want done only 
at login.

Toby Harness		Ogburn/Stouffer Center, University of Chicago
			...ihnp4!gargoyle!toby