Re: [PATCHv2 4/4] git submodule: Fix handling of // and /.. in paths for added submodules

From: Junio C Hamano <gitster@pobox.com>
Date: Feb 25, 2009, 21:25 UTC
Message-ID: <7v1vtm1a6b.fsf@gitster.siamese.dyndns.org>
In-Reply-To: <49A55DAD.2000309@viscovery.net>

Johannes Sixt <j.sixt@viscovery.net> writes:

Show 33 quoted lines

> Michael J Gruber schrieb:
>> Johannes Sixt venit, vidit, dixit 25.02.2009 15:06:
>>> I think we have so far avoided \+ in sed expressions for portability reasons.
>> 
>> Hmmpf. Is it that new, or gnu specific? I'm always afraid of portability
>> issues with bash but wasn't aware of sed being an issue as well.
>> 
>> In any case, would 's|\\*|/|g' be better (more portable) then?
>
> You mean 's|//*|/|g'; yes, that is definitly portable.
>
>> Well, how is
>> 
>> echo a/b/c/../../d | sed -e ':start;s|\([^/]*\)/\.\./||g;tstart'
>> a/d
>> 
>> I meant: how portable is...
>
> I don't know... Let's see: My AIX 4.3.3 sed understands it if it is not
> all on a single line, and that says a lot. Specifically, I tried this:
>
> echo a/b/c/../../d | sed -e ':start
>              s|\([^/]*\)/\.\./||
>              tstart
> '
>
> and got the desired result:
>
> a/d
>
> Note that the 'g' flag is not necessary in this case.
>
> OTOH, this sed doesn't understand #comments :-/

Historically, sed was much worse than the shell when it came to the portability issues, especially before people started to use bash, which tipped the balance a bit by worsening the situation for the shell side.

The sed scripts in the more important parts of scripted Porcelains avoid multiple commands on a single line concatenated with ";" mostly by inertia on my side, but it was acquired exactly from this kind of portability mess. IIRC, AIX's was the worst offender. It also got "/A/../B/ { ... }" wrong in earlier versions.