sed - remove nul lines from file

[James B. Byrne]

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.

-- 
***          e-Mail is NOT a SECURE channel          ***
        Do NOT transmit sensitive data via e-Mail
 Do NOT open attachments nor follow links sent by e-Mail

James B. Byrne                mailto:ByrneJB at Harte-Lyne.ca
Harte & Lyne Limited          http://www.harte-lyne.ca
9 Brockley Drive              vox: +1 905 561 1241
Hamilton, Ontario             fax: +1 905 561 0757
Canada  L8E 3C3