Date: Tue, 7 Nov 2017 13:46:44 -0500 From: "James B. Byrne" <byrnejb@harte-lyne.ca> To: "Yuri Pankov" <yuripv@gmx.com> Cc: freebsd-questions@freebsd.org Subject: Re: sed - remove nul lines from file Message-ID: <f1f862f2f9cf02c5040c7c1acfa77d89.squirrel@webmail.harte-lyne.ca> In-Reply-To: <656b08b1-b79d-8e7e-27ec-e39d883f2355@gmx.com> References: <b21bf201363c34a90ab55c4a05ff8fd7.squirrel@webmail.harte-lyne.ca> <88a59a82-2902-9f63-0a94-bd23b910e7ad@gmx.com> <c2b1ffce6933bcb8f47c856a40d29b16.squirrel@webmail.harte-lyne.ca> <f51d6c8a-c91c-dc7c-6134-e276ec60b179@gmx.com> <88b1870184a8810072fe503917cd86be.squirrel@webmail.harte-lyne.ca> <c00693b7-ae1b-4aa8-49e2-81296cfb281f@gmx.com> <656b08b1-b79d-8e7e-27ec-e39d883f2355@gmx.com>
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On Tue, November 7, 2017 13:28, Yuri Pankov wrote:
> On Tue, 7 Nov 2017 21:20:40 +0300, Yuri Pankov wrote:
>> On Tue, 7 Nov 2017 13:14:08 -0500, James B Byrne Via
>> Freebsd-questions
>> wrote:
>>>
>>> On Tue, November 7, 2017 13:03, Yuri Pankov wrote:
>>>
>>>>
>>>> You want /d, not /g, to delete the *lines* which contain NUL
>>>> symbols
>>>> (that's what your subject line said).
>>>>
>>>
>>> Sigh. Thank you. That works. However, it also deletes any line
>>> that
>>> has even one NUL in it regardless of the presence of other non-nul
>>> characters on the line.
>>>
>>> What I wish to accomplish is to delete only the lines that are
>>> completely nul. I thought that this could be accomplished by
>>> prefacing the match sting with the start of line anchor ^ and
>>> ending
>>> it with the end of line anchor $ but this does not work as I
>>> expect.
>>
>> "[[.NUL.]]" is just a character specified by its collation name, so
>> treat as any other ordinary character:
>>
>> sed -E '/^[[.NUL.]]+$/d' INFILE > OUTFILE
>>
>> Need extended regexp here for '+' to work.
>
>
> Or, after looking at re_format(7), it could be written using BREs,
> your
> choice :-)
>
> sed '/^[[.NUL.]]\{1,\}$/d'
>
sed '/^[[.NUL.]]\{0,\}$/d' INFILE > OUTFILE
Which has no effect. OUTFILE and INFILE remain identical. I get the
exact same result from the first invocation as well. Likewise:
sed '/^[[.NUL.]]\{1,\}$/d' INFILE > OUTFILE
and
sed -E '/^[[.NUL.]]+$/d' INFILE > OUTFILE
# diff INFILE OUTFILE
#
# ll INFILE OUTFILE
-rw-r--r-- 1 root wheel 61480 Nov 7 13:09 INFILE
-rw-r--r-- 1 root wheel 61480 Nov 7 13:38 OUTFILE
I had actually tried these combinations, or at least I believe that I
tried these, before I wrote. Given the complexity and arcane nature
of whatever flavour of RE one is working with I may have transgressed
and written them slightly differently. But the examples you provided
me with give the results I obtained exactly.
--
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