deleting previous 'n' lines of matching the pattern

[Suhas!]

Hi all,

how can I delete previous n number of lines of matching pattern..

I know how to delete the lines after the matching pattern using sed command

sed -e '/pattern1/,/pattern2/d' filename

but I am searching for deleting previous 3 lines of matching pattern.....

I am doing this because I want to delete all the lease entries matching MAC address....

Please help....

[peter]

Try using "grep -n -B <lines> <string>". That will give the number of lines before a matching string and the line numbers.

You could then keep the line numbers in an array and then delete each line afterwards.

[Suhas!]

Thanks!

Now I've gotta find out how to delete lines if we know the line number... probably I have to use sed script... if you know then please let me know how can I do it......


Thanks for your reply...

[redhead]

I am doing this because I want to delete all the lease entries matching MAC address....

What is wrong with something simple, like:

 egrep -v '(DHCPREQUEST | DHCPACK | DHCPDISCOVER | DHCPOFFER)' -e TH:EM:AC:AD:DR:AS /var/log/messages