Re: Patch for install-sh; adds support for -C option

[Ralf Wildenhues]

Hi Marcel,

* Marcel Loose wrote on Wed, Dec 28, 2005 at 03:59:04PM CET:
>  
> I was wondering why install-sh does not support the BSD install -C
> option (install file, unless target already exists and is the same as
> the new file). I consider this option quite useful, especially since
> automake uses install-sh whenever you install header files prefixed
> with nobase_ (see my bug report in GNATS database, #475).

There seems to be no attachment with the bug report.  In any case
though, I guess this will explain why install-sh is used:
http://lists.gnu.org/archive/html/automake-patches/2001-10/msg00131.html
It may be possible to achieve the same effect without using it; but be
warned that install-sh is distributed because on some systems it will be
necessary to use it, so it's not portable to expect extra functionality
of $INSTALL.

> So, I cooked up this patch (see attachment) for install-sh. I have no
> idea whether it meets your quality standards, since this is the very
> first patch I'm uploading. Please send feedback (positive or
> negative), so I can learn.

I think the patch idea ok (but I am not to decide), except for a minor
nit below; it would probably help the maintainer to base it off the CVS
in-source version of install-sh, which is somewhat newer (and then use
`$dst' instead of `$dstdir/$dstfile').

| @@ -264,6 +271,12 @@
|      trap 'ret=$?; rm -f "$dsttmp" "$rmtmp" && exit $ret' 0
|      trap '(exit $?); exit' 1 2 13 15
| 
| +    # If -C was supplied, then *only* copy the source file if
| +    # source and destination are different.
| +    test -n "$instifmod" \
| +    && $doit $cmpprog "$src" "$dstdir/$dstfile" >/dev/null 2>&1 \

I would not dump stdout, only stderr, so that doit=echo remains useful,
and then use `cmp -s' as default cmpprog.  Just a suggestion though.

(Also, the preferred layout style in this file seems to be to put the
`&&' at the end of the line and no following `\'.)

| +    && continue
| +
|      # Copy the file name to the temp name.
|      $doit $cpprog "$src" "$dsttmp" &&

Cheers,
Ralf