sed - remove nul lines from file

James B. Byrne byrnejb at
Tue Nov 7 18:54:45 UTC 2017

On Tue, November 7, 2017 13:36, Polytropon wrote:
> On Tue, 7 Nov 2017 12:12:55 -0500, James B. Byrne via
> freebsd-questions wrote:
>> I have a data file created by an ancient proprietary scripting
>> language called QTP.  There is a bug in this program which, on
>> occasion, manifests itself by inserting output records consisting
>> entirely of nul (^@) (\x00) bytes at regular intervals.  In the
>> present case every 47th. record consists entirely of nuls.
> In this case, awk can also help:
> 	$ awk '(length > 0)' < infile.txt > outfile.txt
> This will print all lines which are longer than 0 characters.

Thank you very much. This worked exactly as I required.

I infer from this that awk does not consider nul a character and its
presence does not count towards the length of a record.  Which is
counter intuitive to me.  A nul takes up the same space as any other
character so why is it not counted?  I would not have tried this
construction for that reason.

***          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 Limited
9 Brockley Drive              vox: +1 905 561 1241
Hamilton, Ontario             fax: +1 905 561 0757
Canada  L8E 3C3

More information about the freebsd-questions mailing list