open LOG, "mylogfile.txt" or die "Cannot open file $!";
while (<LOG>) {
 #do some stuff with data
}

close LOG;

##</code><code>##

open LOG, "mylogfile.txt" or die "Cannot open file $!";
while (<LOG>) {
 print $_; 
 # this will print out the value of $_ so you can 
 # check it to make sure it is what you want to be
 # processing.
}

close LOG;