topic Re: Trim a file in Operating System - HP-UX

Trim a file

Coolmar — Mon, 28 May 2007 09:43:28 GMT

We have a huge file that we need to remove the first 5000 lines from. We can't use "sed" because we can't pipe it to a new file. We need to remove the lines right from the original.

Thanks!

Re: Trim a file

Ivan Ferreira — Mon, 28 May 2007 09:54:35 GMT

Create a file called delete_lines.vi like this:

:1,20 d
:wq

Then run vi in this way:

vi - trimfile < delete_lines.vi

Basically, what you are doing is to run vi in "batch" mode executing the commands indicated in delete_lines.vi

Re: Trim a file

Coolmar — Mon, 28 May 2007 09:56:30 GMT

The problem with vi is that the file is too large for the memory...otherwise he would just do a dd within vi. Is there another way?

Re: Trim a file

Geoff Wild — Mon, 28 May 2007 10:08:04 GMT

Remove the first 5000?

How many does that leave? 100?

tail - 100 > tempfile
cat tempfile > origfile

Rgds...Geoff

Re: Trim a file

Coolmar — Mon, 28 May 2007 10:10:07 GMT

No, it leaves around 200,000....that is why I need to trim that file as is. I cannot manipulate it and write it to another file.

Re: Trim a file

James R. Ferguson — Mon, 28 May 2007 10:15:51 GMT

Hi:

# perl -ni.old -e 'next if 1..5000;print' file

This will perform an "inplace" update of 'file' leaving an unmodified copy as 'file.old'. If you don't want to save the unmodified copy, use :

# perl -ne 'next if 1..5000;print' file

Regards!

...JRF...

Re: Trim a file

Ivan Ferreira — Mon, 28 May 2007 10:21:31 GMT

One last try, with the ex editor this time:

cat delete_lines.ex
1,5000 d
x

ex - file < delete_lines.ex

Re: Trim a file

Coolmar — Mon, 28 May 2007 10:24:01 GMT

Thanks for the responses guys....I went with James' as it was exactly what I was looking for.

Re: Trim a file

Ivan Ferreira — Mon, 28 May 2007 10:25:26 GMT

I really need to learn perl right now! =(