From: Vineet Kumar <vineet@doorstop.net>
Date: Sat, 22 Sep 2007 07:34:46 GMT
Subject: Re: [PATCH] Allow shell scripts to run with non-Bash /bin/sh
Message-ID: <20070922073446.GA3903@doorstop.net>
In-Reply-To: <7vd4wbgp9t.fsf@gitster.siamese.dyndns.org>

* Junio C Hamano (gitster@pobox.com) [070921 23:58]:
> 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
-- 
http://www.doorstop.net/