use IO::Select;

# code to initialize $sock

my $sel = new IO::Select( $sock );

while (1){
  if ($sel->can_read(5 * 60)){ # see if $sock has data.
                               # wait no longer than 5 min
    while (<$sock>){
      # read however many lines you expect
    }

  }else{
    # log error
  }

} #end while