Date: Fri, 5 Mar 2021 22:07:04 -0700 From: Gary Aitken <freebsd@dreamchaser.org> To: Kyle Evans <kevans@freebsd.org> Cc: FreeBSD Mailing List <freebsd-questions@freebsd.org> Subject: Re: sed -i empty argument compatibility issue Message-ID: <f89c2931-ae39-37c4-9638-f0ab39884c3f@dreamchaser.org> In-Reply-To: <CACNAnaGNj55KkSEZOoEqtMVOXtFpk5Ek9tEKJJYARWUGgpwCcw@mail.gmail.com> References: <9178f6c5-631a-c2c2-c6b1-8def94a3397b@dreamchaser.org> <CACNAnaGNj55KkSEZOoEqtMVOXtFpk5Ek9tEKJJYARWUGgpwCcw@mail.gmail.com>
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On 3/5/21 9:39 PM, Kyle Evans wrote:
> On Fri, Mar 5, 2021 at 3:03 PM Gary Aitken <freebsd@dreamchaser.org> 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.)
>>
>> COMMAND sed -i "/^# /d" "${outfile}"
>>
>> The issue is that linux sed expects the -I or -i extension modifier to
>> immediately follow the -i. In the above line, the extension is deliberately
>> missing to provide in-place editing.
>>
>> fbsd expects the extension to be separated from the -i by whitespace, or
>> doesn't work properly when it is empty or immediately follows the -i:
>>
>> $ !ls
>> ls -lt temp.tmp*
>> -rw------- 1 garya garya 86 Mar 5 13:15 temp.tmp
>> -rw------- 1 garya garya 86 Mar 5 13:15 temp.tmp_org
>> $ sed -ifoo "/^# /d" temp.tmp (works on both fbsd & linux))
>> $ !ls
>> ls -lt temp.tmp*
>> -rw------- 1 garya garya 30 Mar 5 13:48 temp.tmp
>> -rw------- 1 garya garya 86 Mar 5 13:15 temp.tmp_org
>> -rw------- 1 garya garya 86 Mar 5 13:15 temp.tmpfoo
>> $ cp -p temp.tmp_org temp.tmp
>> $ sed -i"" "/^# /d" temp.tmp (works on linux but not fbsd)
>> sed: 1: "temp.tmp": undefined label 'emp.tmp'
>> $ sed -i "" "/^# /d" temp.tmp (works on fbsd but not linux)
>> $ !ls
>> ls -lt temp.tmp*
>> -rw------- 1 garya garya 30 Mar 5 13:49 temp.tmp
>> -rw------- 1 garya garya 86 Mar 5 13:15 temp.tmp_org
>> -rw------- 1 garya garya 86 Mar 5 13:15 temp.tmpfoo
>>
>> So fbsd works with '-i ""' but linux requires '-i""'
>>
>> Does anyone know a work-around for this problem?
>>
>
> My personal favorite trick to bridge the gap here was, as I recall:
>
> sed -i'' '' 's/../.../' ${file}
>
> IIRC those sed's with an optional backup suffix (Linux, OpenBSD) will
> accept the immediately following empty string and accept the next
> empty word as an empty command, while our getopt will effectively
> ignore the rest of the -i word and use the following optarg as usual.
Unfortunately, times appear to have changed, at least on ubuntu-18.04:
$ sed -i'' '' "/^# /d" temp.tmp
sed: can't read /^# /d: No such file or directory
Gary
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