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

Microsoft Remote Desktop 8.0.16 - Connec...
With Microsoft Remote Desktop, you can connect to a remote PC and your work resources from almost anywhere. Experience the power of Windows with RemoteFX in a Remote Desktop client designed to help... Read more
Spotify 1.0.4.90. - Stream music, create...
Spotify is a streaming music service that gives you on-demand access to millions of songs. Whether you like driving rock, silky R&B, or grandiose classical music, Spotify's massive catalogue puts... Read more
djay Pro 1.1 - Transform your Mac into a...
djay Pro provides a complete toolkit for performing DJs. Its unique modern interface is built around a sophisticated integration with iTunes and Spotify, giving you instant access to millions of... Read more
Vivaldi 1.0.118.19 - Lightweight browser...
Vivaldi browser. In 1994, two programmers started working on a web browser. Our idea was to make a really fast browser, capable of running on limited hardware, keeping in mind that users are... Read more
Stacks 2.6.11 - New way to create pages...
Stacks is a new way to create pages in RapidWeaver. It's a plugin designed to combine drag-and-drop simplicity with the power of fluid layout. Features: Fluid Layout: Stacks lets you build pages... Read more
xScope 4.1.3 - Onscreen graphic measurem...
xScope is powerful set of tools that are ideal for measuring, inspecting, and testing on-screen graphics and layouts. Its tools float above your desktop windows and can be accessed via a toolbar,... Read more
Cyberduck 4.7 - FTP and SFTP browser. (F...
Cyberduck is a robust FTP/FTP-TLS/SFTP browser for the Mac whose lack of visual clutter and cleverly intuitive features make it easy to use. Support for external editors and system technologies such... Read more
Labels & Addresses 1.7 - Powerful la...
Labels & Addresses is a home and office tool for printing all sorts of labels, envelopes, inventory labels, and price tags. Merge-printing capability makes the program a great tool for holiday... Read more
teleport 1.2.1 - Use one mouse/keyboard...
teleport is a simple utility to let you use one single mouse and keyboard to control several of your Macs. Simply reach the edge of your screen, and your mouse teleports to your other Mac! The... Read more
Apple iMovie 10.0.8 - Edit personal vide...
With an all-new design, Apple iMovie lets you enjoy your videos like never before. Browse your clips more easily, instantly share your favorite moments, and create beautiful HD movies and Hollywood-... Read more

Use Batting Average and the Apple Watch...
Batting Average, by Pixolini, is designed to help you manage your statistics. Every time you go to bat, you can use your Apple Watch to track  your swings, strikes, and hits. [Read more] | Read more »
Celebrate Studio Pango's 3rd Annive...
It is time to party, Pangoland pals! Studio Pango is celebrating their 3rd birthday and their gift to you is a new update to Pangoland. [Read more] | Read more »
Become the World's Most Important D...
Must Deliver, by cherrypick games, is a top-down endless-runner witha healthy dose of the living dead. [Read more] | Read more »
SoundHound + LiveLyrics is Making its De...
SoundHound Inc. has announced that SoundHound + LiveLyrics, will be one of the first third-party apps to hit the Apple Watch. With  SoundHound you'll be able to tap on your watch and have the app recognize the music you are listening to, then have... | Read more »
Adobe Joins the Apple Watch Lineup With...
A whole tidal wave of apps are headed for the Apple Watch, and Adobe has joined in with 3 new ways to enhance your creativity and collaborate with others. The watch apps pair with iPad/iPhone apps to give you total control over your Adobe projects... | Read more »
Z Steel Soldiers, Sequel to Kavcom'...
Kavcom has released Z Steel Soldiers, which continues the story of the comedic RTS originally created by the Bitmap Brothers. [Read more] | Read more »
Seene Lets You Create 3D Images With You...
Seene, by Obvious Engineering, is a 3D capture app that's meant to allow you to create visually stunning 3D images with a tap of your finger, and then share them as a 3D photo, video or gif. [Read more] | Read more »
Lost Within - Tips, Tricks, and Strategi...
Have you just downloaded Lost Within and are you in need of a guiding hand? While it’s not the toughest of games out there you might still want some helpful tips to get you started. [Read more] | Read more »
Entertain Your Pet With Your Watch With...
The Petcube Camera is a device that lets you use live video to check in on your pet, talk to them, and play with them using a laser pointer - all while you're away. And the Petcube app is coming to the Apple Watch, so you'll be able to hang out with... | Read more »
Now You Can Manage Your Line2 Calls With...
You'll be able to get your Line2 cloud phone service on the Apple Watch very soon. The watch app can send and receive messages using hands-free voice dictation, or by selecting from a list of provided responses. [Read more] | Read more »

Price Scanner via MacPrices.net

Intel Compute Stick: A New Mini-Computing For...
The Intel Compute Stick, a new pocket-sized computer based on a quad-core Intel Atom processor running Windows 8.1 with Bing, is available now through Intel Authorized Dealers across much of the... Read more
Heal to Launch First One-Touch House Call Doc...
Santa Monica, California based Heal, a pioneer in on-demand personal health care services — will offer the first one-touch, on-demand house call doctor app for the Apple Watch. Heal’s Watch app,... Read more
Mac Notebooks: Avoiding MagSafe Power Adapter...
Apple Support says proper usage, care, and maintenance of Your Mac notebook’s MagSafe power adapter can substantially increase the the adapter’s service life. Of course, MagSafe itself is an Apple... Read more
12″ Retina MacBook In Shootout With Air And P...
BareFeats’ rob-ART morgan has posted another comparison of the 12″ MacBook with other Mac laptops, noting that the general goodness of all Mac laptops can make which one to purchase a tough decision... Read more
FileMaker Go for iPad and iPhone: Over 1.5 Mi...
FileMaker has announced that its FileMaker Go for iPad and iPhone app has surpassed 1.5 million downloads from the iTunes App Store. The milestone confirms the continued popularity of the FileMaker... Read more
Sale! 13-inch 2.7GHz Retina MacBook Pro for $...
 Best Buy has the new 2015 13″ 2.7GHz/128GB Retina MacBook Pro on sale for $1099 – $200 off MSRP. Choose free shipping or free local store pickup (if available). Price for online orders only, in-... Read more
Minimalist MacBook Confirms Death of Steve Jo...
ReadWrite’s Adriana Lee has posted a eulogy for the “Digital Hub” concept Steve Jobs first proposed back in 2001, declaring the new 12-inch MacBook with its single, over-subscribed USB-C port to be... Read more
13-inch 2.7GHz Retina MacBook Pro for $1234 w...
Adorama has the 13″ 2.7GHz/128GB Retina MacBook Pro in stock for $1234.99 ($65 off MSRP) including free shipping plus a free LG external DVD/CD optical drive. Adorama charges sales tax in NY & NJ... Read more
13-inch 2.5GHz MacBook Pro available for $999...
 Adorama has the 13-inch 2.5GHz MacBook Pro on sale for $999 including free shipping plus NY & NJ sales tax only. Their price is $100 off MSRP. Read more
Save up to $600 with Apple refurbished Mac Pr...
The Apple Store is offering Apple Certified Refurbished Mac Pros for up to $600 off the cost of new models. An Apple one-year warranty is included with each Mac Pro, and shipping is free. The... Read more

Jobs Board

*Apple* Retail - Multiple Positions (US) - A...
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
*Apple* Support Technician IV - Jack Henry a...
Job Description Jack Henry & Associates is seeking an Apple Support Technician. This position while acting independently, ensures the proper day-to-day control of Read more
*Apple* Client Systems Solution Specialist -...
…drive revenue and profit in assigned sales segment and/or region specific to the Apple brand and product sets. This person will work directly with CDW Account Managers Read more
*Apple* Software Support - Casper (Can work...
…experience . Full knowledge of Mac OS X and prior . Mac OSX / Server . Apple Remote Desktop . Process Documentation . Ability to prioritize multiple tasks in a fast pace Read more
*Apple* Software Support - Xerox Corporation...
…Imaging experience Full knowledge of Mac OS X and prior Mac OSX / Server Apple Remote Desktop Process Documentation Ability to prioritize multiple tasks in a fast pace Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.