TweetFollow Us on Twitter

Still More Perl

Volume Number: 19 (2003)
Issue Number: 1
Column Tag: Section 7

Still More Perl

Munging Mail and Media...

by Rich Morin

Perl's "whipitupitude" is legendary. This column looks at a couple of small scripts I've recently been "whipping up", showing how Perl can work in and around more formal OSX tools. One script, fmmf, Finds Monster Mail Files; I use it to keep track of mailing list (and other) mail files which may be getting out of hand. The other script, cfwc.d, is a daemon (background process) which helps me operate an experimental webcam.

Finding MOnster Mail Files

I'm on quite a few mailing lists and I don't always get to the associated mailboxes regularly to keep them under control. I'm also trying to track the efficacy of my spam filtering system (based on SpamAssassin and Eudora), which drops suspected spam into one of several mailboxes, depending on its numeric spam rating, etc. I have written a short script which helps me keep on top of these issues.

The mainline code, below, is quite simple. Using finddepth, from the File::Find module (available on the CPAN; cpan.perl.org), it performs a depth-first examination of my email folder. The callback function, wanted, is invoked for each node (e.g., file, directory) in the tree. Using the lists produced by this traversal, the remaining code prints out the results for spam and miscellaneous email, sorting each list in a case-insensitive manner.

#!/usr/bin/env perl
#
# fmmf - find monster mail files
#
# Written by Rich Morin, CFCL, 2002.11
use File::Find;
$monster = 2000000;
{
  $eu = '/Users/rdm/Mail/Eudora Folder';
  finddepth(\&wanted, "$eu/Mail Folder");
  for $line (sort {lc($a) cmp lc($b)} (@spam)) {
    print $line;
  }
  print "\n";
  for $line (sort {lc($a) cmp lc($b)} (@misc)) {
    print $line;
  }
}

The tricky parts of this script, such as they are, lie in the "wanted" callback function. As it traverses the tree, finddepth changes the "current directory" and sets $_ to the relative name of the node. This makes it easy to skip over items that aren't files and Eudora's "table of contents" (*.toc) files.

sub wanted {
  return unless (-f $_);
  return if ($_ =~ m|\.toc$|);

For the next part, however, we need the "full path name" of the node. Getting this from a handy helper method, we can strip off the first part of the path and test the remainder in assorted ways. Perl's regular expressions are very useful for this sort of name handling.

  $path = $File::Find::name;
  $path =~ s|^.*/Eudora Folder/Mail Folder/||;
  return if ($path =~ m|_Inactive/ Save/|);

After picking up the size of the file (in bytes), the script opens each mailbox in the "spam" area and counts the number of "From: headers (i.e., messages). Eudora uses carriage returns (rather than the conventional BSD newlines) for line termination, but setting Perl's $/ (input record separator) variable handles that quite easily. The strings containing the formatted output are pushed into a list, for use by the mainline code.

  $size = -s $_;
  if ($path =~ m|!Spam|) {
    open(MBOX, $_) or die "can't open mailbox($_)";
    $/ = "\r";
    $fcnt = 0;
    while (defined($line = <MBOX>)) {
      $fcnt++ if ($line =~ m|^From:|) ;
    } 
    close(MBOX);
    push(@spam, sprintf("%-35s  %9d  %4d\n",
      $path, $size, $fcnt));
    return;
  }

The code for miscellaneous mailboxes is comparatively simple. After ensuring that the mailbox is large enough to qualify as a "monster", it formats and saves the output lines. Perl's "x" operator comes in handy for creating a "quick and dirty" histogram.

  return if ($size < $monster);
  $isiz = int($size/$monster);
  push(@misc, sprintf("%-35s  %9d  %s\n",
    $path, $size, '*' x $isiz));
}

This sort of "personalized" script is quite common in BSD circles. Clearly, it isn't suitable for use by others, as is, but it is short and simple enough that it can easily be customized to meet the needs of different users. Here is some sample output, from my own system:

!Spam/?? Junk (Eudora)                9041     5
!Spam/?? Junk (SA 1)                 39192     6
!Spam/?? Junk (SA 2)                 11467     2
!Spam/?? Junk (SA 3)                420538    60
_Lists/DocBook                     3231686  *
_Lists/FreeBSD/FreeBSD-Ports       6431902  ***
_Lists/FreeBSD/FreeBSD-Questions   2666962  *
...

A WebCam Daemon

I recently started playing with an iBOT, a FireWire-based camera made by Orange Micro

(www.orangemicro.com). My initial goal was to create a simple "security camera" app that would display a set of recent images on a web page.

After downloading the OSX driver for the iBOT, I started looking around for image capture software. One package, EvoCam (www.evological.com), captures images, based on elapsed time and/or software-based motion detection. It can also upload the image files (via FTP) to a web server and/or save numbered copies on the local disk.

Unfortunately, this wasn't exactly what I wanted. The FTP upload feature simply refreshed the same file; turning this into a time history would be tricky. The numbered image files would do, however, if I could get them over to the web server. All told, it was a good start on what I wanted. All I needed to do was create a little plumbing...

The first part of the plumbing had to do with getting the files from my desktop Mac onto the (FreeBSD-based) local web server. FreeBSD provides NFS, but getting OSX to mount the provided volumes can be quite a trial. Fortunately, Marcel Bresink's NFS Manager (www.bresink.de/osx/NFSManager.html) eases the pain considerably.

Once I got the files sifting into a directory on the web server, I merely had to rename them (for convenience) and build up a web page to display a selected subset. The following script, while still a "work in progress", accomplishes these tasks quite handily.

#!/usr/bin/env perl
#
# cfwc.d - Canta Forda WebCam Daemon
#
# Written by Rich Morin, CFCL, 2002.11
$imgs = '/.../iBOT';   # adjust to taste...
$html = '/.../cfwc';   # adjust to taste...
{
  for (;;) {

As mentioned above, EvoCam generates a unique name (e.g., 123456789.jpg) for each image file. In writing these to the NFS-mounted FreeBSD machine, OSX also generates a companion file (e.g., ._123456789.jpg) for the resource fork. The code below creates a new name for the image file, based on the file's modification time, and discards the companion file.

    # Clean out incoming directory.
    opendir(IN, "$imgs/incoming")
      or die "can't open $imgs/incoming";
    @in = grep(!/^\./, readdir(IN));
    chomp(@in);
    closedir(IN);
    for $in (sort(@in)) {
      @stat = stat("$imgs/incoming/$in");
      $mtime = $stat[9];
      ($sec, $min, $hour, $mday, $mon, $year,
       $wday, $yday, $isdst) = localtime($mtime);
      $out = sprintf("%d.%02d%02d.%02d%02d%02d.jpg",
        $year+1900, $mon+1, $mday, $hour, $min, $sec);
      rename("$imgs/incoming/$in",
             "$imgs/i.queue/$out");
      unlink("$imgs/incoming/._$in"); 
    }

Perl's approach to reading directories is rather messy, but it isn't all that difficult. The code below gets a list of filenames, discarding any that don't match the desired format, and sorts them. Because the names were crafted with this in mind, the list is now in chronological order.

    # Get list of images to display.
    opendir(IN, "$imgs/i.queue")
      or die "can't open $imgs/i.queue";
    @in  = sort(grep(/^\d{4}\.\d{4}\.\d{6}\.jpg$/,
                     readdir(IN)));
    chomp(@in);
    closedir(IN);

Using Perl's "slice" syntax, we grab the last (i.e., most recent) nine file names.

    @show = @in[-9 .. -1];

Now we start generating a web page. The META tag tells the user's browser to refresh the page every 15 seconds. I am rather compulsive about formatting the HTML; the web browser doesn't care, but it sure makes debugging less painful for humans!

    # Make up a new web page.
    open(OUT, ">$html/index.temp")
      or die "can't open index.temp";
    print OUT <<EOT;
<HTML>
  <HEAD>
    <META HTTP-EQUIV="Refresh" content="15">
    <TITLE>Canta Forda WebCam</TITLE>
  </HEAD>
  <BODY>
    <TABLE>
EOT

The code below generates a 3x3 table of images, each followed by a centered label. I could have used the file names (e.g., 2002.1129.2039.jpg) as labels, but that would have been a bit ugly. Why not parse the names and reformat the values into a more readable format?

Note the multi-line regular expression that is used to break up the file name. When REs get long and complex, breaking them up in this manner can make them much easier to follow.

    $cnt = 0;
    for ($i=0; $i<9; $i+=3) {
      print OUT "      <TR>\n";
      for ($j=0; $j<3; $j++) {
        print OUT "        <TD>\n";
        $k = $i + $j;
        $tmp1 = $show[$k];
        $tmp1 =~
          m|^(\d{4})\.            # (YYYY).
             (\d\d)(\d\d)\.       # (MM)(DD).
             (\d\d)(\d\d)(\d\d)\. # (HH)(MM)(SS).
             jpg$|x;              # jpg
        $tmp2 = sprintf("%s/%s/%s at %s:%s:%s",
                        $1, $2, $3, $4, $5, $6);
        print OUT "          <CENTER>\n";
        print OUT "            ",
                  "<IMG SRC=\"iq/$tmp1\"><BR>\n";
        print OUT "            $tmp2\n";
        print OUT "          </CENTER>\n";
        $cnt++;
        print OUT "        </TD>\n";
      }
      print OUT "      </TR>\n";
    }

Finally, we push out the last of the HTML, close the file and (Oh, yes!) move it into place for Apache to find. Then, after a second's repose, we go back up and do the whole exercise again.

    print OUT <<EOT;
    </TABLE>
  </BODY>
<HTML>
EOT
    close(OUT);
    rename("$html/index.temp",
           "$html/index.html");
    sleep(1);
  } 
}

Lessons Learned

As we all know, the Mac and BSD universes aren't a perfect fit. Perl is a very good "glue language", however, allowing us to deal smoothly with issues such as line termination, extra (e.g., resource fork) files, etc.

Similarly, there are a wealth of useful apps which can perform small tasks, fill in gaps between operating systems, and generally make our lives easier. If a $20 shareware package can save me hours of frustration, the purchase decision is a no-brainer.

Unfortunately, some issues are still difficult to resolve. For instance, although it's easy to scan a Eudora mail file for header lines, editing Eudora mailboxes would be far trickier. Aside from file locking problems, there is the small issue of the (binary, undocumented) format of the TOC files. In short, choose your challenges carefully...


Rich Morin has been using computers since 1970, Unix since 1983, and Mac-based Unix since 1986 (when he helped Apple create A/UX 1.0). When he isn't writing this column, Rich runs Prime Time Freeware (www.ptf.com), a publisher of books and CD-ROMs for the Free and Open Source software community. Feel free to write to Rich at rdm@ptf.com.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Civilization VI 1.0.1 - Next iteration o...
Sid Meier’s Civilization VI is the next entry in the popular Civilization franchise. Originally created by legendary game designer Sid Meier, Civilization is a strategy game in which you attempt to... Read more
Chromium 55.0.2883.75 - Fast and stable...
Chromium is an open-source browser project that aims to build a safer, faster, and more stable way for all Internet users to experience the web. Version 55.0.2883.75: Security fixes: High CVE-2016... Read more
Google Chrome 55.0.2883.75 - Modern and...
Google Chrome is a Web browser by Google, created to be a modern platform for Web pages and applications. It utilizes very fast loading of Web pages and has a V8 engine, which is a custom built... Read more
VirtualBox 5.1.10 - x86 virtualization s...
VirtualBox is a family of powerful x86 virtualization products for enterprise as well as home use. Not only is VirtualBox an extremely feature rich, high performance product for enterprise customers... Read more
Pixa 1.1.9 - Quickly and easily organize...
Pixa is an image-organizing application. The new app functions well, is easy to use, and helps people organize their images quickly and easily on their computers. For those who prefer not to use the... Read more
VirtualBox 5.1.10 - x86 virtualization s...
VirtualBox is a family of powerful x86 virtualization products for enterprise as well as home use. Not only is VirtualBox an extremely feature rich, high performance product for enterprise customers... Read more
Pixa 1.1.9 - Quickly and easily organize...
Pixa is an image-organizing application. The new app functions well, is easy to use, and helps people organize their images quickly and easily on their computers. For those who prefer not to use the... Read more
Civilization VI 1.0.1 - Next iteration o...
Sid Meier’s Civilization VI is the next entry in the popular Civilization franchise. Originally created by legendary game designer Sid Meier, Civilization is a strategy game in which you attempt to... Read more
Google Chrome 55.0.2883.75 - Modern and...
Google Chrome is a Web browser by Google, created to be a modern platform for Web pages and applications. It utilizes very fast loading of Web pages and has a V8 engine, which is a custom built... Read more
Chromium 55.0.2883.75 - Fast and stable...
Chromium is an open-source browser project that aims to build a safer, faster, and more stable way for all Internet users to experience the web. Version 55.0.2883.75: Security fixes: High CVE-2016... Read more

Latest Forum Discussions

See All

Amateur Surgeon 4 Guide: Become the worl...
It's time to wield your trusty pizza cutter again, as Amateur Surgeon has returned with a whole fresh set of challenges (and some old, familiar ones, too). Starting anew isn't easy, especially when all you have at your disposal is a lighter, the... | Read more »
Le Parker: Sous Chef Extraordinaire (Ga...
Le Parker: Sous Chef Extraordinaire 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: | Read more »
Telltale Games really is working on a Gu...
Telltale Games' next episodic adventure is indeed Guardians of the Galaxy. A document tied to the voice actors strike suggested that the project was in the work, but now we have direct confirmation following an announcement at the Game Awards that... | Read more »
Amateur Surgeon returns to iOS and Andro...
Amateur Surgeon and its two sequels disappeared from the App Store some time and it was sad days for all. But now, just in time for the holidays, the Adult Swim favorite makes its joyous return in the shape of Amateur Surgeon 4, a remake with... | Read more »
The best board games on mobile
Sometimes you need to ditch all of the high speed, high action games in favor of something a little more traditional. If you don't feel like parting ways from your mobile device, though, there are still plenty of ways to get that old-school fix.... | Read more »
The best Facebook Messenger Instant Game...
Facebook's new Instant Games is now here, meaning you can play games with your friends directly via Facebook. It's a fun new way to connect with friends, of course, but it's also proving to be a solid gaming experience in its own right, with a... | Read more »
You can now play game's on Facebook...
Facebook launched its new Instant Games platform in an exciting new attempt to engage its user base. As a result, you can now play a number of different games directly through Facebook Messenger. All of these games run with HTML5, meaning you play... | Read more »
Apollo Justice Ace Attorney (Games)
Apollo Justice Ace Attorney 1.00.00 Device: iOS Universal Category: Games Price: $.99, Version: 1.00.00 (iTunes) Description: Court Is Back In Session Star as rookie defense attorney, Apollo Justice, as he visits crime scenes,... | Read more »
KORG iWAVESTATION (Music)
KORG iWAVESTATION 1.0 Device: iOS Universal Category: Music Price: $19.99, Version: 1.0 (iTunes) Description: A revolutionary new world of sound.The Wave Sequence Synthesizer for iPad - KORG iWAVESTATION | Read more »
Don't Grind Guide: Tips for becomin...
Don’t Grind is a surprising, derpy little one touch game with fun hand-drawn graphics. The goal is simple -- get the high score without being chopped to bits. That can be tough when you’re not used to the game, and that’s compounded by the fact... | Read more »

Price Scanner via MacPrices.net

13-inch Silver Touch Bar MacBook Pro in stock...
Amazon has the new 2016 13″ 2.9GHz/256GB Silver Touch Bar MacBook Pro (MLVP2LL/A) in stock today and on sale for $1749 including free shipping. That’s $50 off MSRP, and it’s the lowest price... Read more
Parallels Toolbox 1.3 for Mac Offers 25 Singl...
Parallels has launched Parallels Toolbox 1.3 for Mac, an upgrade that adds five new utilities to the stand-alone application which was released in August and is available exclusively online at http... Read more
OWC Mercury Elite Pro Dual mini Ultra-Portabl...
OWC has introduced the new OWC Mercury Elite Pro Dual mini, a powerful yet ultra-portable dual-drive RAID solution. The new Mercury Elite Pro Dual mini packs phenomenal performance into a small... Read more
Clearance 13-inch Retina MacBook Pros availab...
B&H Photo has clearance 2015 13″ Retina Apple MacBook Pros available for up to $200 off original MSRP. Shipping is free, and B&H charges NY tax only: - 13″ 2.7GHz/128GB Retina MacBook Pro: $... Read more
Roundup of 2016 13-inch 2.0GHz MacBook Pro sa...
B&H has the non-Touch Bar 13″ MacBook Pros in stock today for $50-$100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.0GHz MacBook Pro Space Gray (MLL42LL/A): $1449 $... Read more
New 13-inch 2.0GHz Space Gray MacBook Pro in...
Adorama has the new 13″ 2.0GHz Space Gray MacBook Pro (non-Touch Bar, MLL42LL/A) in stock for $1499 including a free 3-year AppleCare Protection Plan. Shipping is free, and Adorama charges sales tax... Read more
Finnair Adopts iOS Enterprise iPad Apps from...
Finnair and IBM have announced a first-of-its-kind agreement to utilize iOS enterprise apps from IBM to support the airline’s overall digital transformation. Finnair is focused on Asia-Europe traffic... Read more
Tech21 Launches Evo Go iPhone 7 Case Availabl...
Tech21 has announced the launch of the Evo Go case for Apple iPhone 7 and iPhone 7 Plus, exclusively at T-Mobile. Available online and at participating T-Mobile stores nationwide, Evo Go cases start... Read more
Apple Turns (RED) with More Ways to Join the...
In recognition of World AIDS Day, Apple is offering more ways than ever for customers to join (RED) in its mission to create an AIDS-free generation. Apple is the worlds largest corporate contributor... Read more
Deals on new 15-inch Touch Bar MacBook Pros,...
B&H Photo has new 2016 Apple 15″ Touch Bar MacBook Pro models in stock today with some available for $50 off MSRP, each including free shipping plus NY sales tax only: - 15″ 2.7GHz Touch Bar... Read more

Jobs Board

*Apple* Brand Ambassador (Macy's) - The...
…(T-ROC), is proud of its unprecedented relationship with our partner and client, APPLE ,in bringing amazing" APPLE ADVOCATES"to "non" Apple store locations. Read more
US- *Apple* Store Leader Program - Apple (Un...
…Summary Learn and grow as you explore the art of leadership at the Apple Store. You'll master our retail business inside and out through training, hands-on Read more
*Apple* Retail - Multiple Positions- White P...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
Automotive Detailer - *Apple* Used Autos -...
We are currently conductinginterviews and will be accepting applications for a part-time detailer. Apple Used Autos is a great place to work andstart a career. We Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.