my $prev;
while (<>) {
    if (not defined $prev or $prev ne $ARGV) {
        print "now reading from $ARGV\n";
    }
    print;
    $prev = $ARGV;
}

##</code><code>##

while (<>) {
    if (not defined $prev or $prev ne $ARGV) {
        print "reading $ARGV\n";
    }

    print;

    print "and that's the end of $ARGV\n" if (eof);
    $prev = $ARGV;
}