#!/usr/bin/perl -w

my $targetF = "/var/log/local2";

for(;;) {
    open ML, "<$targetF" || die $!;
    #seek(ML, 0, 2); # to EOF - Not, process from beginning
    
    for (;;){
        while (<ML>){
            another_line();
        }
        sleep 2;
        seek(ML,  0, 1); # reset end-of-file error
    }
    # dropping here with the 'last' should cause
    # the file being monitored to be closed and reopened
    close (ML);
}

sub another_line {
    # $_ has the line
    # Check for target phrases
    return;
}