topic Delete first lines from text file in Operating System - HP-UX

Delete first lines from text file

Mauro_8 — Thu, 26 Dec 2002 17:15:57 GMT

Hi,

I want to delete the first lines from text file and keep only the last 50 lines of the file. How can I do it ? Using sed ?

Cheers,
Mauro

Re: Delete first lines from text file

Justo Exposito — Thu, 26 Dec 2002 17:24:40 GMT

Hi Mauro,

You can use tail -50 fichname > fichtmp

Regards,

Justo.

Re: Delete first lines from text file

Uday_S_Ankolekar — Thu, 26 Dec 2002 17:24:56 GMT

Easy way would be..

tail -50 filename > newname

-USA..

Re: Delete first lines from text file

Justo Exposito — Thu, 26 Dec 2002 17:38:46 GMT

Hi Mauro,

With sed is like:
num=`wc -l fich| cut -d" " -f1`
(( num1=num - 50 ))
sed -e ''$num1','$num'd' fich

Regards,

Justo.

Re: Delete first lines from text file

Justo Exposito — Thu, 26 Dec 2002 17:40:43 GMT

Hi Again,

You must observe that in this line:
sed -e ''$num1','$num'd' fich
before $ character are two ' characters and not one ".

Regards,

Justo.

Re: Delete first lines from text file

Mauro_8 — Thu, 26 Dec 2002 18:08:15 GMT

Hi,

I just want to open the file, delete the lines and close it without distroying the file because this file is a log file and a process writes in this file continuosly if I have to rename to a temp file and then back it to orginal name this process will lose the point.

Thanks once more,
Mauro

Re: Delete first lines from text file

Nelson Mina — Thu, 26 Dec 2002 18:31:06 GMT

tail -50 logfile > newfile
cat newfile > logfile

This won't close the pointer to the file. You have a slight risk of loosing data if it was written to the log file after the "tail" but before the "cat" command.