Tag Archive for irc

Using IRC to set Reminders with the “at” Command


Remind me at 5pm to go to the bank

You can use IRC to remind you to do anything. Now that you have a directory that your IRC bot reads, you can use one of Linux’s best kept secrets: the at command. The at command allows you to schedule one-time jobs to be run in the future — a non-reoccurring cronjob. The real win with using at is its time syntax. Here’s a few examples from the man page:

  • to run a job at 4pm three days from now, you would do at 4pm + 3 day
  • to run a job at 10:00am on July 31, you would do at 10am Jul 31
  • to run a job at 1am tomorrow, you would do at 1am tomorrow.

You can use this to run any command or script at a given time. This makes the at command perfect for usage over IRC — we just need to drop a file with the reminder in the /say directory at the given time. It’s easy to wrap some of this syntax to give the reminder command a human-like syntax.


I went with the following syntax, best expressed with a summarized version of the regular expression used to parse it:

 ^(remind|pm) (me|us|everyone) (at|in|on) (.*?) to (.*)$

You might say the following things in the IRC channel to the bot:

  • remind me in 5 minutes to check the dryer
  • pm me at 10pm to remember to charge my cell phone
  • remind everyone on august 1s to enjoy the weather

These commands all get sent to at. Behind the scenes, the bot does the following:

  1. creates a file under /var/tmp with the contents of the reminder. The filename follows the format mentioned in the Mixing the Command-Line and IRC post, and sets the unique identifier to a hash of the submitter’s nick and current timestamp.
  2. the at command is instructed to move the file from /var/tmp/ to the ~/say directory at the requested time
  3. at the requested time, at moves the file and the bot picks it up and prints it to the channel.

There’s only a small amount of additional wrapping needed to make the interaction fluid. The biggest abstraction is in the difference between the “remind me at/on” and “remind me in” commands. “remind me at/on” passes the date straight through to the at command, where “in” prepends “now +” to the request. That’s it!

The channel has been using the reminder feature more and more. It’s nice to set a reminder with a long article you’d like to read, or set a reminder in 2 weeks to write a blog post for the DeadCoderSociety. Socializing reminders is a great way to increase community interaction and raise awareness for interesting information that might otherwise end up on a sticky note in a pocket somewhere.


The other Friday I was talking about payday and one guy had added a reminder to “GET PAID” for the next set of pairs of weeks. We ended up adding this on the command-line:

for i in `seq 12 2 50`; do
    echo 'echo "GET PAID" > /srv/git/neilforobot/say/#dcs@paid' | 
    at now + $i weeks ; 

At makes setting these types of reminders up easy!

Mixing the Command-Line and IRC bots


Making cookies with IRC and the command-line

My IRC bot checks a directory every minute for files and reads the contents into a channel. This simple feature is also one of my favorites.

The loop:

  1. Checks for the presence of files under /say.
  2. Reads the contents of the file into a string.
  3. Prints the contents into a channel (pulled from filename).
  4. Removes the file.

Mix crontab into this and you can use any of your favorite commandline tools. Here’s a few examples from my own usage:

Finance tip at 8AM every day:

00 08 * * * curl -sLk http://bit.ly/OowzSt -o ~/say/#finance@tip

This just hits a PHP script that returns a random money tip. Note: The @ sign is being used to separate the name of the channel and a unique identifier for the file. Multiple files can land in the directory without one overwriting the other.

Top HackerNews link at 1PM:

00 13 * * * ~/cronjobs/hackernews.pl > ~/say/#dcs@hn

Note: The original job was a one liner using Mojolicious:

perl -Mojo -E 'say g("http://hackerne.ws")->dom->at("tr > td.title > a")->tree->[2]->{href}'

It’s been expanded since to include the title and keep the crontab clean.

One-off website update checker:

* * * * * curl -s http://stantheman.biz | diff file1 -
|| echo 'The page changed!' > ~/say/msg@stan_theman@update

This is a quick cheap way of being automatically alerted to changes on a website.

Note: You could easily toss this into a shell script and do some more work to update the file being diffed. This would let you know about continued changes. The current script will ping you until you remove the cronjob in this state. You also need to curl the page into file1 before installing the script — I said it was cheap!

You can use this for any short piece of information (RSS feed updates, system mail, CPU/disk usage). I’ll continue with my other favorite use for this in the next blog post.

DeadCoderSociety IRC channel

The DeadCoderSociety is now a registered Freenode group! You can join us in #dcs on irc.freenode.org. Use the web IRC client in the top-right corner to join us without the hassles of setting up a local IRC client. A special thanks to Jason Schollenberger for getting us set up with Freenode.

Cheers to the DeadCoderSociety!