Re: [PATCH] test-lib.sh: use awk instead of expr for a POSIX non integer check

From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mar 11, 2022, 23:02 UTC
Message-ID: <CAPig+cQT3801Fok9Uvk1TOs5WscdM+hRX7x3sW38izRqAR1N1A@mail.gmail.com>
In-Reply-To: <xmqqv8wnm30q.fsf@gitster.g>

On Wed, Mar 9, 2022 at 12:47 PM Junio C Hamano <gitster@pobox.com> wrote:

Show 17 quoted lines

> Eric Sunshine <sunshine@sunshineco.com> writes:
> > On Tue, Mar 8, 2022 at 6:58 PM Eric Sunshine <sunshine@sunshineco.com> wrote:
> >> > On Tue, Mar 8, 2022 at 6:44 PM Carlo Marcelo Arenas Belón
> >> > <carenas@gmail.com> wrote:
> >> > > +               local _GLIBC_VERSION=$(getconf GNU_LIBC_VERSION 2>/dev/null)
> >> > > +               if echo "$_GLIBC_VERSION" | cut -d. -f1-2 |
> >> > > +                       awk '{ if ($2 - 2.34 < 0) exit 1 }'
> >
> > This seems to work, though it's getting a bit verbose:
> >
> >     awk '/^glibc / { split($2,v,"."); if (sprintf("%s.%s", v[1], v[2])
> > - 2.34 < 0) exit 1 }'
>
> If we are losing "cut" (which I think is a good thing to do), we
> probably can lose the pipe, too and refer to $_GLIBC_VERSION as an
> element in ARGV[] and make the command used as "if" condition to a
> single "awk" script?

Erm, something like this perhaps?

    awk 'BEGIN { split(ARGV[1], v, "[ .]"); if (v[1]=="glibc" &&
sprintf("%s.%s", v[2], v[3]) - 2.34 < 0) exit 1 }'

Show 6 quoted lines

> In general it is a good discipline to question a pipeline that
> preprocesses input fed to a script written in a language with full
> programming power like awk and perl (and to lessor extent, sed) to
> see if we can come up with a simpler solution without pipeline
> helping to solve what these languages are invented to solve, and I
> very much appreciate your exploration ;-)

Yup, although in this case, the pure-awk solution may not convey the intent as easily as the original posted by Carlo which had the benefit of being perhaps easier to digest.