From: Jeff King <peff@peff.net>
Date: Wed, 26 Sep 2018 03:21:08 GMT
Subject: Re: [PATCH v2 2/3] transport.c: introduce core.alternateRefsCommand
Message-ID: <20180926032107.GB32064@sigill.intra.peff.net>
In-Reply-To: <20180926010606.GJ4364@syl>

On Tue, Sep 25, 2018 at 06:06:06PM -0700, Taylor Blau wrote:

> > > +extract_haves () {
> > > +	depacketize - | grep '\.have' | sed -e 's/\\0.*$//g'
> > > +}
> >
> > Don't pipe grep into sed, especially when both the pattern to filter
> > and the operation to perform are simple.
> >
> > I am not sure what you are trying to achive with 'g' in
> > s/pattern$//g; The anchor at the rightmost end of the pattern makes
> > sure that the pattern matches only once per line at the end anyway,
> > so "do this howmanyever times as we have match on each line" would
> > not make any difference, no?
> 
> I admit to not fully understanding when the trailing `/g` is and is not
> useful. Anyway, I took Peff's suggestion below to convert this 'grep |
> sed' pipeline into a Perl invocation, which I think ended up much
> cleaner.

It makes the replacement global in the line. Without we substitute only
the first match. So try:

  echo foo | sed s/o/X/

versus:

  echo foo | sed s/o/X/g

-Peff