Hi all,

I know the one liner to delete all the lines in a file which matches a pattern
i.e

perl -i.old -ne 'print unless /pattern/' file

Now i need the perl onliner to delete all the lines which doesnt match the pattern. Also what is the difference between perl -i and perl -i.old.
Does perl -i.old archive the existing file?

Your help in this will be appreciated.

Thanks in advance.

Lijju

Only print lines matching the pattern:

perl -i.old -ne 'print if /pattern/' file