ArsDigita Archives

ArsDigita Watchdog

for AOLserver by Terence Collins and Philip Greenspun, part of ArsDigita Free Tools
ArsDigita Watchdog is a system that monitors your AOLserver's error log at regular, short intervals, and notifies the necessary individuals via email. In keeping with ArsDigita's server architecture philosophy, if you are maintaining multiple services, or just one service that sees a lot of traffic, you want to save yourself the trouble of opening up the log file(s) in emacs and then poring over the logs to discover errors strewn amidst various notices and errors you'd rather ignore. ArsDigita Watchdog allows you to:
  • Specify multiple maintainers to notify of errors occuring in your log.
  • Specify individuals to notify of errors only occuring in certain subdirectories.
  • Specify patterns of errors of which you'd rather not be notified.
Watchdog is built using AOLserver (free) and takes advantage of AOLserver's built-in scheduler (like Unix cron but lighter weight) and Tcl API. However, unlike most of our AOLserver products, you don't need to install an RDBMS in order to use Watchdog. Web servers generally get stuck because of problems with the RDBMS, so a monitor that depended on an RDBMS would be self-defeating.

Watchdog is written to match the format and peculiarities of the AOLserver error log, however the source is freely available and can be hacked to handle other servers' error logs.


  • Download watchdog.tar.gz (last updated April 30, 1999)
  • cd /web
  • tar xvf watchdog.tar.gz (creates /web/watchdog.dist)
  • mv watchdog.dist watchdog
  • Create an AOLserver whose page root is /web/watchdog and whose private Tcl directory is /web/watchdog/tcl. Alternatively, you could install watchdog as a subdirectory in another web server, so long as you symlink the watchdog .tcl files from your server's tcl directory.
  • Edit /tcl/defs.tcl to set the main Watchdog parameters.
  • Make sure your watchdog directory is writable by nsadmin.
  • You're done! Start your server

Bug Fixes

  • April 30, 1999: fixed bug wherein watchdog would stop running if an error file could not be found


This is open-source software, copyright 1998 ArsDigita, LLC and licensed under the GNU General Public License.

Support and Customization

If you want a extended version of Watchdog or support, you can hire the programmer of your choice to install, maintain, and customize Watchdog. ArsDigita offers support as well, but probably not at a price that you'd be happy to pay.