From mboxrd@z Thu Jan  1 00:00:00 1970
From: Johannes Sixt <J.Sixt@eudaptics.com>
Subject: Re: [PATCH] filter-branch: Avoid an error message in the map function.
Date: Wed, 04 Jul 2007 13:45:22 +0200
Organization: eudaptics software gmbh
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Cc: Johannes Sixt <johannes.sixt@telecom.at>, gitster@pobox.com,
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To: Johannes Schindelin <Johannes.Schindelin@gmx.de>
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Johannes Schindelin wrote:
> 
> Hi,
> 
> On Wed, 4 Jul 2007, Johannes Sixt wrote:
> 
> > -     test -r "$workdir/../map/$1" || echo "$1"
> > -     cat "$workdir/../map/$1"
> > +     test -r "$workdir/../map/$1" &&
> > +     cat "$workdir/../map/$1" ||
> > +     echo "$1"
> 
> I think this does not do what you want. If I read it correctly, it will
> not do anything if $workdir/../map/$1 is not readable. I think you need
> this:
> 
>         (test -r "$workdir/../map/$1" &&
>         cat "$workdir/../map/$1") ||
>         echo "$1"
> 
> But that is a little too cute, so I personally would prefer an
> if-then-else-fi, because that is the idea of that code snippet.

It does do what I think it should do. I tested it. Your elaborate
version is not required. The reason is that in the shell && and || have
equal precedence; if there is ... && cmd ... then cmd is run if the most
recent result is success, and if there is ... || cmd ... then cmd is run
if the most recent result is failure; in both cases cmd is otherwise
skipped and does not count as "most recent result".

-- Hannes