Date: Sun, 19 Jul 2009 21:08:00 -0400 From: Glen Barber <glen.j.barber@gmail.com> To: Mark Andrews <marka@isc.org> Cc: stable@freebsd.org Subject: Re: Shell execution ( [was] Re: Value of $? lost in the beginning of a function.) Message-ID: <4ad871310907191808g8a81107wa17799284be176a@mail.gmail.com> In-Reply-To: <200907200102.n6K12h1Y048534@drugs.dv.isc.org> References: <4ad871310907191717g1ed90be7y92250f2addc38d43@mail.gmail.com> <200907200102.n6K12h1Y048534@drugs.dv.isc.org>
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On Sun, Jul 19, 2009 at 9:02 PM, Mark Andrews<marka@isc.org> wrote: > > In message <4ad871310907191717g1ed90be7y92250f2addc38d43@mail.gmail.com>,= Glen > Barber writes: >> Possibly off-topic... >> >> >> 2009/7/19 Glen Barber <glen.j.barber@gmail.com>: >> > 2009/7/19 Romain Tarti=3DE8re <romain@blogreen.org>: >> >> Hi Glen, >> >> >> >> On Sun, Jul 19, 2009 at 04:32:28PM -0400, Glen Barber wrote: >> >>> > % sh foo.sh >> >>> > % zsh foo.sh >> >>> > % bash foo.sh >> >>> What happens if you replace '#!/bin/sh' with '#!/usr/local/bin/zsh' = ? >> >> >> >> This is not related to my problem since I am not running the script >> >> using ./foo.sh but directly using the proper shell. =3DA0sh just beha= ves >> >> differently, that looks odd so I would like to know if it is a bug in= sh >> >> or if there is no specification for this and the behaviour depends of >> >> the implementation of each shell, in which case I have to tweak the >> >> script I am porting to avoid this construct (passing $? as an argumen= t >> >> for example). >> >> >> >> Romain >> >> >> > >> > My understanding was this: >> > >> > If you specify 'sh foo.sh' at the shell, the script will be run in a >> > /bin/sh shell, _unless_ you override the shell _in_ the script. >> > >> > Ie, 'sh foo.sh' containing '#!/bin/sh' being redundant, but 'zsh >> > foo.sh' containing '#!/bin/sh' would execute using zsh. >> > >> > >> >> I meant to say in the last line: "'#!/bin/sh' would override the 'zsh' s= hel=3D >> l." >> >> Can someone enlighten me if I am wrong about this? >> > > "#!" is used to define the interpretor when the file is exec'd. > > perl, AFAIK, is the only interpretor that will look at what is after > the "#!" and modify it's behaviour. =A0All other a interpretors (shells) > treat "#!" as a comment. > > Some shells used to examine the executable about to be called and > looked for "#!" and invoke the correct interpretor. =A0This was how > "#!" was supported before kernels has support for "#!". =A0It was all > done in userland. > Hi, Mark. You've given me enough information to point me in the right direction on digging further into this. Thanks, and I appreciate the response! --=20 Glen Barber
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