From: Francis Hwang <sera@...>
Date: 2004-11-11T22:44:51+09:00
Subject: Writing a looping, low-configuration script in Ruby

So I'm writing a one-file Ruby program that will generate an RSS feed 
every half-hour, and I want it to have as little configuration as 
possible. This is aimed both at Rubyists and newcomers who might be 
pulled into the Rubyverse by another well-targeted tool, so I'm trying 
to think of the clearest, easiest way that the user could configure 
this.

So here's what I'm thinking: If this has to run every 30 minutes, the 
easiest way (for me, the programmer) to do this, is have the user run 
it as a backgrounded process:

$ ./script.rb &

but that's sort of fragile, particularly since (if I'm understand Unix 
process correctly) backgrounding is handled in the shell so you can't 
really log out without killing the background. Also, if you restart the 
web server you lose the process, too.

So then I was thinking: Can I have a config that automatically edits 
the crontab? Has anybody used Ruby to programmatically edit a crontab? 
I suppose the brute force way to do it is to call "crontab -e" and send 
the various keystrokes to stdin, but I wonder if anybody knows of a 
less duct-tapey way.

F.