Re: [PATCH] Allow shell scripts to run with non-Bash /bin/sh

From: Vineet Kumar <vineet@doorstop.net>
Date: Sep 22, 2007, 07:34 UTC
Message-ID: <20070922073446.GA3903@doorstop.net>
In-Reply-To: <7vd4wbgp9t.fsf@gitster.siamese.dyndns.org>

* Junio C Hamano (gitster@pobox.com) [070921 23:58]:

Show 30 quoted lines

> David Kastrup <dak@gnu.org> writes:
> 
> > Eygene Ryabinkin <rea-git@codelabs.ru> writes:
> >
> >>> That is, what does the shell say if you do this?
> >>> 
> >>> 	case Ultra in
> >>>         Super)
> >>>         	false ;;
> >>> 	Hyper)
> >>>         	true ;;
> >>> 	esac &&
> >>>         echo case returned ok
> >>
> >> It says 'case returned ok', so I will try to understand why it
> >> works here and does not work in the 'while' construct.
> >
> > What you actually need to do is
> >
> > false
> > case Ultra in
> >    Super)
> >    	false ;;
> > Hyper)
> >    	true ;;
> > esac && echo case returned ok
> 
> AHHHHHH.
> 
> Is "case" supposed to be transparent?

That doesn't seem to be the case (no pun intended) on either bash or dash. Here's what I tested on bash (apologies for the long lines; these are verbatim pastes from my shell):

vineet@sprocket:~$ false vineet@sprocket:~$ case Super in Super) echo super ; false ;; Hyper) echo hyper ; true ;; esac && echo case returned ok super vineet@sprocket:~$ false vineet@sprocket:~$ case Hyper in Super) echo super ; false ;; Hyper) echo hyper ; true ;; esac && echo case returned ok hyper case returned ok vineet@sprocket:~$ false vineet@sprocket:~$ case Ultra in Super) echo super ; false ;; Hyper) echo hyper ; true ;; esac && echo case returned ok case returned ok vineet@sprocket:~$

and on dash:

vineet@sprocket:~$ dash $ false $ case Super in Super) echo super ; false ;; Hyper) echo hyper ; true ;; esac && echo case returned ok super $ false $ case Hyper in Super) echo super ; false ;; Hyper) echo hyper ; true ;; esac && echo case returned ok hyper case returned ok $ false $ case Ultra in Super) echo super ; false ;; Hyper) echo hyper ; true ;; esac && echo case returned ok case returned ok $

So it seems like a "case" statement isn't special; it returns a status like any other statement.

Vineet

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