in reply to Namechange

In the spirit of giving a man a fish, go ahead and try this one-liner on each of the files you need changed:

perl -i.bak -pe's=\@xyz\.com=\@xyzabc.com=g;'

This can be done very easily in Perl, but this one-liner will not help you if the text you are trying to replace spans two lines. (The -i.bak bit makes a backup of the files you change, but be careful, anyway.)

--
Allolex

Update: Shamelessly escaped the @s according to diotalevi's and nvuku's good advice. I seem to be having a sloppy night. /me goes off to look for mistakes in other nodes.