Date: Fri, 5 Mar 2021 20:50:46 -0700 From: Gary Aitken <freebsd@dreamchaser.org> To: freebsd-questions@freebsd.org Subject: Re: sed -i empty argument compatibility issue Message-ID: <606b8bfa-4fe5-883a-d7ac-99f41655f728@dreamchaser.org> In-Reply-To: <20210305142352297368817@bob.proulx.com> References: <9178f6c5-631a-c2c2-c6b1-8def94a3397b@dreamchaser.org> <20210305142352297368817@bob.proulx.com>
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On 3/5/21 2:43 PM, Bob Proulx wrote:
> Gary Aitken wrote:
>> I'm trying to come up with a fix for a script in a port which
>> invokes sed. The port comes from a linux environment, and the
>> offending line looks like this: (This is in a cMake file.)
...> In order to port this then _something_ must be changed. As to what
> must be changed that is up to you and judegement and the larger view
> of everything in your environment. But off the top of my head these
> different possibilities come to mind.
>
> 1. Edit the script and change this to that. This makes it run on
> FreeBSD sed. Of course then this does not work the other direction.
>
> -COMMAND sed -i "/^# /d" "${outfile}" +COMMAND sed -i "" "/^# /d"
> "${outfile}"
>
> 2. Use perl. Change that edit command to be this. This should work
> the same everywhere that has perl. It does create a dependency upon
> perl that might not have been present before.
>
> perl -i -lpe 'next if /^# /' "${outfile}"
>
> 3. Avoid -i and use a temporary file, just like in the old days.
> However this introduces the need for temporary file handling. But
> maybe that isn't important here.
>
> sed "/^# /d" "${outfile}" > "$tmpfile" && mv "$tmpfile" "${outfile}"
>
> 4. Introduce a "sed" wrapper in PATH that intercepts the call to the
> real sed, detects this problematic usage case, and then DTRT does
> the right thing with it. This wrapper could have all of the correct
> temporary file handling needed to make this work. More involved to
> do this but if I were faced with a large unknown code base and
> expected to see a lot of this then I would consider it a good global
> workaround for portability.
>
> 5. Hack a local FreeBSD sed version to detect this case and DTRT
> with the option.
>
> 6. Compile GNU sed locally and install it in PATH earlier. This
> would probably be a generally good option globally. However it's
> possible you might run into portability problems in the reverse
> case.
Thanks for the list. That's two more than I came up with. I'm
inclined to #2 (which I hadn't thought of) or #3.
> Good luck! I'll be interested in hearing how things work out for
> you.
Thanks. I'm asking the authors for feedback.
Gary
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