From: Logan Capaldo <logancapaldo@...>
Date: 2004-11-12T04:56:49+09:00
Subject: Re: Writing a looping, low-configuration script in Ruby

Well if you don't want to fiddle with crontabs and keep it
cross-platform, rather than doing ./script.rb & you could look into
Process.fork

something like

$ cat runevery30mins.rb
#!/usr/bin/env ruby

Process.fork do
         loop
              generate_rss_feed
              sleep(30 * 60)
         end
end

then simply

$ ./runevery30mins.rb
$

It will immediately exit but fork into another process that will
generate a new rss feed every 30 minutes

Obviously you may want to add some way of stopping it (short of killing it)
perhaps with Drb.


On Fri, 12 Nov 2004 03:03:17 +0900, Francis Hwang <sera@fhwang.net> wrote:
> Cool! Funny that stuff isn't in the man page. Thanks much.
> 
> 
> 
> On Nov 11, 2004, at 9:09 AM, Florian Frank wrote:
> 
> > On 2004-11-11 22:44:51 +0900, Francis Hwang wrote:
> >> 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.
> >
> > You can install a new crontab with
> > $ crontab filename
> > or
> > $ crontab -
> > for stdin input.
> >
> > You can output the current crontab of $USER with
> > $ crontab -l > filename
> >
> > Of course you can do this in a ruby script, too. In this case you
> > should
> > perhaps use a lock file.
> >
> > If you only want to run a script every 30 minutes with cron, you
> > can add a line like
> > */30 * * * *    /path/to/script.rb
> > to your crontab. This is actually one of the main reasons to install
> > something like cron.
> >
> > --
> > Florian Frank
> >
> 
>