[tpm] Fast(er) way of deleting X lines from start of a file

Alex Beamish talexb at gmail.com
Wed Sep 30 08:57:27 PDT 2009

On Wed, Sep 30, 2009 at 11:39 AM, Madison Kelly <linux at alteeve.com> wrote:
> Hi all,
>  Thus far, I've opened a file, read it in, shifted/ignored the first X
> number of line and then wrote out the resulting file. This works, but
> strikes me as horribly inefficient. Doubly so when the file could be larger
> than RAM.
>  So then, is there a more efficient/faster way of saying "Delete the first X
> number of lines from file foo"?

I would expect you could fashion something workable like this

  #  Get the number of lines in the file ..
  wc -l file

  #  tail the desired number of lines to a new file ..
  tail -n $numberOfLinesInFile-$numberOfLinesYouDontWant file >newfile

  #  and move the files around.
  rm file; mv newfile file

Alex Beamish
Toronto, Ontario
aka talexb

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