Michał Łomnicki

Recently I’ve started using IRC again. What a great feeling! I use pretty standard technique. My irssi client is run on my server in screen session. I attach to the session via SSH to read and write some gossip.

  ssh -t michal@example.com screen -r

Only one thing bothers me. There is no sign of new messages on IRC channel. I have to switch terminals and check if there is something new.

Remote side

It is quite easy to get notifications having irssi on local machine but getting them from remote machine seems to be slightly more complicated. There is no easy way for remote machine to send us data about new traffic. I don’t want port forwarding or something similar to achieve so silly task. Polling the server seems to be the only way. It would be also nice if the task could be done with persisted connection to avoid connecting again and again.

Other problem: how to know that new message has been sent? I’ve enabled irssi logs. I’m not the irssi expert some maybe there is more accurate way. To enable logs open irssi and type:

  /set autolog

The logs are saved to ~/irclogs/IRC_SERVER/CHANNEL.log

How to monitor them without reconnecting? Simple tail -f to the rescue

  ssh michal@example.com tail -n0 -f ~/irclogs/*/*.log

I’ve also added -q and -n0 arguments.

• -q - don’t print file headers
• -n0 - don’t print trailing lines (by default tail prints 10 trailing lines)

For now on new messages appears on your local terminal.

Notifications

OK, half of the job is done. Now how to display notifications? LibNotify is excellent for that purpose.

  $ apt-get install libnotify-bin
  $ notify-send "hello" "notification sent from my libnotify-bin"

OS X users may use Growl which seems to be very nice tool too.

Join them

We have irc logs forwarded to our host and notification tool. Firstly I wanted to use xargs Finally there will be something about ruby :) Of course perl/python/C or others does their job as well.

  ssh michal@example.com "tail -n0 -f ~/irclogs/*/*.log" | \
   ruby -rshellwords -ne '`notify-send -t 500 #{$_.shellescape}`'

Quick explanation

• -rshellwords means require ‘shellwords’
• -n - read each line from stdin and assign to $_ (for perl lovers)
• -e - exectues ruby code
• `system_command` - executes some_command in your shell (backticks not quotes)
• String.shellescape - prevents your ircmates from executing commands on your machine ;-)

notify-send -t 500 is quite more interesting. Basically it displays notification with 500ms timeout. Official documentation says that. However Ubuntu users have to install patched version. Debian/Gentoo/Fedora/Arch/etc users are OK. Why only Ubuntu? Well, Ubuntu core-team recons theirs users are too dumb to decide about notification timeout. Read ridiculous story here.

Improve

Above oneliner isn’t very sophisticated. There is plenty of room for improvements. For instance to display nickname as notification title and message as notification content only simple change is needed

ssh michal@example.com "tail -q -n0 -f ~/irclogs/*/*.log " | \
   ruby -rshellwords -ne '`notify-send -t 1000 #{$1.shellescape} #{$2.shellescape}`\
     if $_ =~ /<([^>]+)>(.*)/'

Don’t stick to oneliner unnecessarily. More complex scripts should be written to file.