Re: [PATCH v2] config: simplify profile.*sh.in

[Mark Wielaard <mark@klomp.org>]

Hi,

On Wed, 2022-01-19 at 13:31 +0100, наб via Elfutils-devel wrote:
> On Tue, Jan 18, 2022 at 11:13:28AM -0500, Frank Ch. Eigler wrote:
> > You mean "prefix=@prefix@".  And it's not needless,
> > because @sysconfdir@ often expands to "$prefix/something",
> > which requires a prefix var to be set for evaluation.
> 
> I did, and yeah, that's right. Guess it was so outlandish that I
> completely missed it. Dropped.
> 
> > > 2. Simplify needless sh -c "cat glob 2>/dev/null"
> > >    into cat glob 2>/dev/null
> > 
> > This is not needless, but I forget the exact details.  It probably
> > has
> > to do with the $prefix expansion just above, or perhaps glob
> > non-matching error handling.
> 
> Well, no, as-written, it is needless. It's also incorrect,
> since it's subject to word-splitting (=> a broken glob) again.
> 
> But, yeah, turns out csh does have "glob non-matching error handing",
> which is both news to me and a blast from a V3-era past.
> That being said, it was also broken, because under csh
>   false | cat
> fails, for some inexplicable reason, and if the glob "fails",
> so does cat, so so does sh.
> 
> I've restored it, in a fashion that isn't subject to re-splitting,
> and actually protects -e mode, for csh.
> 
> v2 scissor-patch below.
> 
> Please keep me in CC, as I'm not subscribed,
> наб
> 
> -- >8 --
> 1. Simplify needless sh -c "cat glob 2>/dev/null"
>    into cat glob 2>/dev/null under sh
>    and fix re-expansion/-e protection under csh
> 2. Use $( instead of ` under sh
> 3. Assign to D_U directly and either export it or unset it

This seems reasonable to me, but I did have to lookup the exact
workings of sh -c to make sense of it.

  -c string
   If the -c option is present, then commands are read from
   string.  If there are arguments after the string, they are
   assigned to the positional parameters, starting with $0.

I have added a ChangeLog entry:

2022-01-19  Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>

       * profile.csh.in: Set DEBUGINFOD_URLS directly. Use "$0" and :
       in sh -c.
       * profile.sh.in: Set DEBUGINFOD_URLS directly. Don't use sh -c.
       Use $() instead of ``.

Full commit at:
https://code.wildebeest.org/git/user/mjw/elfutils/commit/?h=simplify-profile

Frank, do you have any more concerns with this patch?
Ahelenia, under which shells have you tested this?

Thanks,

Mark