Date: Thu, 1 May 1997 09:31:29 +0200 From: j@uriah.heep.sax.de (J Wunsch) To: hackers@freebsd.org Cc: andrew@erlenstar.demon.co.uk (Andrew Gierth) Subject: Re: /bin/sh -c and ENV Message-ID: <19970501093129.LO56219@uriah.heep.sax.de> In-Reply-To: <87rafr6a0o.fsf@erlenstar.demon.co.uk>; from Andrew Gierth on May 1, 1997 06:23:19 %2B0100 References: <87rafr6a0o.fsf@erlenstar.demon.co.uk>
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As Andrew Gierth wrote:
> Just noticed that /bin/sh is executing the ENV file even when invoked with
> the -c option. Is this a bug or a feature? :-)
Feature.
> (Executing the ENV file in calls to system(3) or popen(3) could be considered
> a Bad Thing, even in non-suid programs, and the last system I used where
> system and popen invoked a Posix shell specifically disabled the ENV file
> if the -c option was used.)
. Suid programs that do system() deserve to be shot immediately; this
can simply be achieved by converting them to suidperl scripts, and
leave it to suidperl to complain about your stupid use of a shell
inside a setuid program. :-)
. If the shell detects that the real and effective UID are different,
option -p is in effect, and no $ENV processing happens anyway.
. If your $ENV file is not bulletproof, go back 10 or 15 years in
history, go to Berkeley, you'll certainly use a csh. You'll then
learn how to write .cshrc files that don't depend on the interactive-
ness of the shell. :-)
For .cshrc:
if ($?prompt) then
# This part only executed in an interactive shell:
alias m less
set history = 100
set filec
endif
For $ENV:
case "$-" in
*i*)
# This part only executed in an interactive shell:
alias m=less
set hmm you can't set history here (though you have one) :-)
set nor do you have filec :-O
esac
--
cheers, J"org
joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)
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