i guess this should help:

readline EXPR;

"Reads from the filehandle whose typeglob is contained in EXPR. In scalar context, each call reads and returns the next line, until end-of-file is reached, whereupon the subsequent call returns undef."

from http://aspn.activestate.com/ASPN/docs/ActivePerl-5.6/lib/Pod/perlfunc.html#item_readline

also have a look at :

http://aspn.activestate.com/ASPN/docs/ActivePerl-5.6/lib/Pod/perlfunc.html#item_seek