Robert Buchholz wrote:
> On Tuesday, 25. September 2007, Donnie Berkholz wrote:
>> On 20:04 Mon 24 Sep , Doug Goldstein (cardoe) wrote:
>> > if ! use usb; then
>> > sed -i util/Makefile \
>> > -e '/ttusb_dec_reset/d' \
>> > -e '/dib3000-watch/d'
>> > fi
>> >
>> > # do not compile test-progs
>> > sed -i Makefile -e '/-C test/d'
>>
>> You might want to die if these seds fail.
>
> I already wondered a while back:
> sed only fails if the file does not exist, but not if there was no
> replacement. Is there any way to force it to?
>
ed will exit with an error if a regex doesn't match:
ed -s util/Makefile <<< 'H
/ttusb_dec_reset/d
/dib3000-watch/d
w
q' || die 'ohNoes!'
I prefer to mute errors in an ebuild (after testing):
ed -s Makefile 2>/dev/null <<< $'/-C test/d\nw\nq' \
|| die 'No match in Makefile'
..which I think is a lot easier to grok than the sed convolutions.
If it's supposed to be deleting every line with that regex (as the sed
currently does) I'd use: $'g/-C test/d\nw\nq'
I appreciate that ed seems hard (man ed is frightening!) but once you get
used to here-strings (and $' expansion) it's a doddle. (Use ,p instead of w
to see the output during testing.)
Tutorial: http://bash-hackers.org/wiki/doku.php?id=howto:edit-ed
Easier man page: http://plan9.bell-labs.com/magic/man2html/1/ed
Reference: http://www.opengroup.org/onlinepubs/009695399/utilities/ed.html
(I very much recommend that opengroup site as it outlines what a scripwriter
or programmer can expect on any POSIX/SuS compliant system.)
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