my @file = <FH>;

##</code><code>##

local *FH;
open(FH, "/path/to/file") || die "Can't open file: $!";
while (<FH>)
{
    # line is in $_
    if ($_ eq $external_info)
    {
        print "great\!";
        last;
    }
}

close(FH);