sub load {
    my ($qfn) = @_;
    open(my $fh, '<', $qfn)
        or die("Can't open file \"$qfn\": $!\n");
    
    my %data;
    local *_;
    while (<$fh>) {
        my ($id) = /^(\S+)/ or next;
        die("Duplicate key $id\n")
            if exists($data{$id});
        $data{$id} = $_;
    }

    return \%data;
}

my $master = eval { load(...) }
    or die("Can't load master db: $@");

my $new = eval { load(...) }
    or die("Can't load new db: $@");

my %ids;
for my $id (keys(%$master), keys(%$new)) {
    next if $ids{$id}++;
    if (!exists($new->{$id})) {
        print("-$master->{$id}");
    }
    elsif (!exists($master->{$id})) {
        print("+$new->{$id}");
    }
    elsif ($master->{$id} ne $new->{$id}) {
        print("-$master->{$id}");
        print("+$new->{$id}");
    }
    else {
        print("=$master->{$id}");
    }
}

[download]

Update: Added missing parens and fixed var name as per reply.

In reply to Re: Search, Match, Compare, and Report by ikegami
in thread Search, Match, Compare, and Report by kirkbrown

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.