Re: [PATCH] bootstrap: take advantage of POSIX shell features

[Jim Meyering]

Stefano Lattarini wrote:
> Hi Jim.
>
> On 05/13/2012 10:31 AM, Jim Meyering wrote:
>>
>>> diff --git a/build-aux/bootstrap b/build-aux/bootstrap
>> ...
>>> @@ -442,7 +442,7 @@ check_versions() {
>>>      # "GNU automake-ng") when asked their version.
>>>      case $app in
>>>        automake-ng|aclocal-ng)
>>> -        app=`echo "$app" | sed 's/-ng$//'`
>>> +        app=${appo%-ng}
>>>          ($app --version | grep '(GNU automake-ng)') >/dev/null 2>&1 || {
>>>            echo "$me: Error: '$app' not found or not from Automake-NG" >&2
>>>            ret=1
>>
>> s/appo/app/
>>
>> It looks fine, modulo that typo.
>> No need to resend.  I'll push it later today or tomorrow.
>>
> Notice that I can push the patch myself, since I have pushing rights for the

Ok.  Even better.

> Gnulib repo.  Also, I think we should add "suggested by Eric Blake" in the
> commit message, since the idea of this patch stemmed from an exchange with
> him.  And finally, I've noticed there's a typo in the commit message: it
> should say '* build-aux/bootstrap', not '* bootstrap'.  So I propose the

If you were to use vc-dwim, it would catch that error right away.

> following amending of the commit message:
>
>   diff --git a/ChangeLog b/ChangeLog
>   index cf73593..6a25a28 100644
>   --- a/ChangeLog
>   +++ b/ChangeLog
>   @@ -11,13 +11,17 @@
>           thus use these features to improve the clarity and the performances
>           of the bootstrap script.
>
>   -       * bootstrap: Prefer xpg4 parameter expansions over use of sed/expr
>   -       plus command substitutions, to save some forks.  Since we are at it,
>   -       prefer the POSIX $(...) form of command substitution, rather than
>   -       the legacy form `...` (since the former is visually clearer and
>   -       interacts better with quoting), and prefer "if ! CMD; then ACTION"
>   -       over the idiom "if CMD; then :; else ACTION" (which was required by
>   -       legacy Bourne shells not supporting '!').
>   +       Suggested by Eric Blake.
>   +
>   +       * build-aux/bootstrap: Prefer xpg4 parameter expansions over use
>   +       of sed/expr plus command substitutions, to save some forks.  Since
>   +       we are at it, prefer the POSIX $(...) form of command substitution,

The idiom is "While we are at it..."

>   +       rather than the legacy form `...` (since the former is visually
>   +       clearer and interacts better with quoting), and prefer the idiom:
>   +         "if ! CMD; then ACTION ..."
>   +       over the idiom:
>   +         "if CMD; then :; else ACTION ..."
>   +       which was required by legacy Bourne shells not supporting '!'.
>
>    2012-05-08  Jim Meyering  <address@hidden>
>
> OK?

Sure.