Earlier this month, I completed yet another journey around the biggest star in our galaxy. Some of my beloved family members thought this would be a good occasion to send me some cash, and I also got a gift card for being plain awesome at work. Even though we really do need a bigger car and whatnot, my wife insisted that I only spend this money on myself and whatever I wanted.

Little did she know the can of worms she just opened up.

I took pretty much all of the money and blew it on stuff for my electronics projects. Up to this point, my projects have all been pretty boring simply because nothing ever moved--it was mostly just lights turning on and off or changing colors. Sure, that's fun, but things really start to get interesting when you actually interact with the physical world. With the birthday money, I was finally able to buy a bunch of servos to begin living out my childhood dream of building robots.

My first project since getting all of my new toys was a motorized webcam mount. My parents bought me a Logitech C910 for my birthday because they were tired of trying to see their grandchildren with the crappy webcam that is built into my laptop. It was a perfect opportunity to use SparkFun's tutorial for some facial tracking (thanks to OpenCV) using their Pan/Tilt Servo Bracket.

It took a little while to get everything setup properly, but SparkFun's tutorial explains perfectly how you can get everything setup if you want to repeat this project.

The problem I had with the SparkFun tutorial, though, is that it basically only gives you a standalone program that does the facial tracking and displays your webcam feed. What good is that? I actually wanted to use this rig to chat with people!! That's when I set out to figure out how to do this.

While the Processing sketch ran absolutely perfect on Windows, it didn't want to work on my Arch Linux system due to some missing dependencies that I didn't know how/care to satisfy. As such, I opted to rewrite the sketch using Python so I could do the facial tracking in Linux.

This is still a work in progress, but here's the current facial tracking program which tells the Arduino where the webcam should be pointing, along with the Arduino sketch.

Now that I could track a face and move my webcam in Linux, I still faced the same problem as before: how can I use my face-tracking, webcam-moving program during a chat with my mom? I had no idea how to accomplish this. I figured I would have to either intercept the webcam feed as it was going to Skype or the Google Talk Plugin, or I'd have to somehow consume the webcam feed and proxy it back out as a V4L2 device that the Google Talk Plugin could then use.

Trying to come up with a way of doing that seemed rather impossible (at least in straight Python), but I eventually stumbled upon a couple little gems.

• A GStreamer webcam tutorial
• v4l2loopback

So the GStreamer tutorial walks you step-by-step through different ways of using a gst-launch utility, and I found this information very useful. I learned that you can use tee to split a webcam feed and do two different things with it. I wondered if it would be possible to split one webcam feed and send it to two other V4L2 devices.

Enter v4l2loopback.

I was able to install this module from Arch's AUR, and using it was super easy (you should be root for this):

modprobe v4l2loopback devices=2

This created two new /dev/video* devices on my system, which happened to be /dev/video4 and /dev/video5 (yeah... been playing with a lot of webcams and whatnot). One device, video4, is for consumption by my face-tracking program. The other, video5, is for VLC, Skype, Google+ Hangouts, etc. After creating those devices, I simply ran the following command as a regular user:

gst-launch-0.10 v4l2src device=/dev/video1 ! \
    'video/x-raw-yuv,width=640,height=480,framerate=30/1' ! \
    tee name=t_vid ! queue ! \
    v4l2sink sync=false device=/dev/video4 t_vid. ! \
    queue ! videorate ! 'video/x-raw-yuv,framerate=30/1' ! \
    v4l2sink device=/dev/video5

There's a whole lot of stuff going on in that command that I honestly do not understand. All I know is that it made it so both my face-tracking Python program AND VLC can consume the same video feed via two different V4L2 devices! A co-worker of mine agreed to have a quick Google+ Hangout with me to test this setup under "real" circumstances (thx man). It worked :D Objective reached!

I had really hoped to find a way to handle this stuff inside Python, but I have to admit that this is a pretty slick setup. A lot of things are still hardcoded, but I do plan on making things a little more generic soon enough.

So here's my little rig (why yes, I did mount it on top of an old Kool-Aid powder thingy lid):

And a video of it in action. Please excuse the subject of the webcam video, I'm not sure where that guy came from or why he's playing with my webcam.

Yay! First post in nearly 4 months! I feel kinda bad for leaving my April Fools Day joke on the front page for such a long time, but lucky for me my blog isn't very popular! I could have found myself in a world of hurt.

I'd like to give you all a quick update on what's been going on in my life that somewhat justifies a 4-month window of no blog posts. First of all, we had 25% of our backend development team (1 person, leaving 3 developers) get fired earlier in the year, so the workload at my day job got to be a bit heavier.

Second, my wife and I were pregnant with identical twin girls. It was a relatively high-risk pregnancy, so we spent many days in the hospital for checkups and whatnot. The doctors gave her somewhat strict bed rest orders, and I worked from home since the beginning of July (my job is awesome that way) so I could keep and eye on my wife and help with our soon-to-be two year old son.

Third, we had our identical twin girls this past Tuesday. They arrived at 9:25 and 9:27, and their names are Claire and Jane. Claire weighed 5 lb 3 oz, and Jane weighed 4 lb 14 oz. As expected, they lost a bit of weight at the beginning, but they're starting to gain weight again. My wife and the girls are all doing very well.

My son, on the other hand, is starting to realize that his world is changing quite drastically. We're trying to give him as much attention as we can, but it's definitely not the amount that he's used to. He seems to do very well with his new baby sisters, but there have already been several episodes where he just breaks down. It's sad.

I have a few days of leave and vacation that I'll be taking to help get everything settle at home. The girls are still in the "let's sleep all day and night until we're hungry" sort of phase (which is quite awesome), and my wife is up most of the night with them. That means the only person who doesn't sleep a ton during the day is my son, so we get some good father/son time.

Anyway, on to the nerdy stuff. Since I find myself with a couple hours of downtime here and there, I plan to do a bug-smashing ticket-resolving spree. Just as my blog has sat dormant for months, so have many of my side projects. Now is the time to change that!

For one reason or another, I've recently had the urge to follow in my father's footsteps and start tinkering with electronics. He's basically a wizard. He has fixed a lot of appliances that others tossed out the door without the slightest bit of investigation. I think he did this with the monitor I had hooked up to my very first computer. He just popped open the case, found the problem, soldered some solution in there, and that monitor worked for probably a decade afterwards. Amazing stuff.

Anyway, I have an itch to create a laser trip wire (don't ask). I took a basic electronics class my freshman year in college, so I am already familiar with resistors, capacitors, ICs, breadboards, soldering, etc. It doesn't seem like a very daunting task to create that trip wire, but I'm starting fresh with electronics (it's been a good 8 or 9 years since I last soldered or anything like that).

One of my co-workers mentioned the Arduino as something to get me started on the trip wire, so I started doing some research here and there. The more I read, the more excited I got. I wanted soo badly to buy all of the junk that I'd need to start tinkering with an Arduino, but I didn't think my wife would appreciate that--especially around Christmas time.

Several of my awesome relatives sent me very generous gift cards for Christmas this year, which finally gave me the opportunity to buy a load of stuff for the Arduino without feeling bad. So I ordered loads of stuff. Most of it is here, some of it is still on its way. My Arduino Uno arrived around noon today, and I haven't been able to stop tinkering! It's really a lot of fun, and stupid easy even if you're not a programmer!

I started with the basic "oooh, blinking LEDs!" sort of projects (or "sketches" in Arduino parlance). Then I moved on to tweak those to work with multiple LEDs. There were a few different scenarios I ran though because two of my LEDs weren't lighting up very well. I guess I either hooked them up wrong or I didn't seat them properly... whatever.

The next project was when I hooked up a PIR (passive infrared) motion sensor ($9.99 at RadioShack) and installed a demo sketch that I found on the Arduino wiki. I wasn't quite sure how to wire everything for the PIR sensor, so I took a look at this Make Magazine video to see one way of setting up the circuit. That one simply lights up an LED and makes some noise. I just made mine light up and LED since I don't have a buzzer (yet).

Next I moved on to the LCD. The package came with a 20x4 green-on-black backlit LCD display, a 2.2k Ohm resistor, and a set of pins to connect the LCD to my breadboard or whatever. I actually soldered the pins onto the LCD display board (wow, was that even more difficult than I remember!) so I would have less of a hassle getting all of the contacts working. Getting the LCD to work was pretty easy after that.

Then I took those two projects a bit further. I'm certain others have done this years ago, but I didn't use a sketch that was completely written for me this time so I felt special enough to share :) I added the PIR circuit from before less the LED, merged pieces from both demo programs, and came up with a motion sensor that would flash "INTRUDER ALERT!!" on the LCD screen a few times when triggered. Based on my testing, the sensor works extremely well (once calibrated!!), and it will detect motion well across the open area of my apartment (maybe a bit further than 20 feet)!

I'm quite happy with my work, especially for not having "dealt with" electronics for such a long time. When I tried to share my success with some of my friends, they wanted a video to prove I'm awesome (I guess?). So here it is. Trust me, I know the video is horrible--I speak too quietly (baby sleeping in next room), I stumble over my words (that's just me), and I neglected to even offer you some music to rock out to as I blabber about this stuff.

Here's the program I wrote/modified:

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 /*
  * //////////////////////////////////////////////////
  * //making sense of the Parallax PIR sensor's output
  * //////////////////////////////////////////////////
  *
  * Switches a LED according to the state of the sensors output pin. Determines
  * the beginning and end of continuous motion sequences.
  *
  * @author: Kristian Gohlke / krigoo (_) gmail (_) com / http://krx.at
  * @author: Josh VanderLinden / codekoala (.) gmail (@) com / http://www.codekoala.com
  * @date:   3 Jan 2011
  *
  * kr1 (cleft) 2006
  * Released under a creative commons "Attribution-NonCommercial-ShareAlike 2.0" license
  * http://creativecommons.org/licenses/by-nc-sa/2.0/de/
  *
  *
  * The Parallax PIR Sensor is an easy to use digital infrared motion sensor module.
  * (http://www.parallax.com/detail.asp?product_id=555-28027)
  *
  * The sensor's output pin goes to HIGH if motion is present. However, even if
  * motion is present it goes to LOW from time to time, which might give the
  * impression no motion is present. This program deals with this issue by
  * ignoring LOW-phases shorter than a given time, assuming continuous motion is
  * present during these phases.
  *
  */

 #include <LiquidCrystal.h>

 int calibrationTime = 10;   // seconds to calibrate PIR
 long unsigned int pause = 5000; // timeout before we "all" motion has ceased
 long unsigned int lowIn; // the time when the sensor outputs a low impulse

 boolean lockLow = true;
 boolean takeLowTime;

 int flashCnt = 4;  // number of times the LCD will flash when there's motion
 int flashDelay = 500; // number of ms to wait while flashing LCD
 int pirPin = 7;    // the digital pin connected to the PIR sensor's output
 int lcdPin = 13;   // pin connected to LCD
 LiquidCrystal lcd(12, 11, 10, 5, 4, 3, 2);

 void setup() {
     // Calibrates the PIR

     Serial.begin(9600);
     pinMode(pirPin, INPUT);
     pinMode(lcdPin, OUTPUT);

     digitalWrite(pirPin, LOW);

     clearLcd();

     // give the sensor some time to calibrate
     lcd.setCursor(0,0);
     lcd.print("Calibrating...");

     for(int i = 0; i < calibrationTime; i++){
         lcd.print(".");
         delay(1000);
     }

     lcd.print("done");
     delay(50);
 }

 void clearLcd() {
     // Clears the LCD, turns off the backlight
     lcd.begin(20, 4);
     lcd.clear();
     digitalWrite(lcdPin, LOW);
 }

 void alertLcd() {
     // Turns on the LCD backlight and notifies user of motion
     lcd.setCursor(2, 1);
     digitalWrite(lcdPin, HIGH);
     lcd.print("INTRUDER ALERT!!");
     lcd.setCursor(2, 2);
     lcd.print("================");
 }

 void loop() {
     // Main execution loop

     if(digitalRead(pirPin) == HIGH) {
         // flash an alert a few times
         for (int c = 0; c < flashCnt; c++) {
             alertLcd();
             delay(flashDelay);
             lcd.clear();
             delay(flashDelay);
         }

         if(lockLow) {
             // makes sure we wait for a transition to LOW before any further
             // output is made:
             lockLow = false;
             delay(50);
         }
         takeLowTime = true;
     }

     if (digitalRead(pirPin) == LOW) {
         clearLcd();

         if (takeLowTime) {
             // save the time of the transition from high to LOW
             // make sure this is only done at the start of a LOW phase
             lowIn = millis();
             takeLowTime = false;
         }

         // if the sensor is low for more than the given pause,
         // we assume that no more motion is going to happen
         if (!lockLow && millis() - lowIn > pause) {
             // makes sure this block of code is only executed again after
             // a new motion sequence has been detected
             lockLow = true;
             delay(50);
         }
     }
 }

I've finally gotten around to looking at a bunch of tickets that had been opened for django-tracking in the past year and a half or so. I feel horrible that it's really taken that long for me to get to them! Every time I got a ticket notification, I told myself, "Okay, I'll work on that this weekend." Many have weekends have passed without any work on any of my projects. I'm going to get better about that!

Anyway, several fixes have gone into the latest version of django-tracking. Some have to do with unicode problems (thanks ramusus!). Others have to do with overall performance, while yet others have to do with overall stability.

The first interesting change in this release is that django-tracking no longer relies on the GeoIP Python API. Instead it's now using django.contrib.gis.utils.GeoIP. I had hoped that this would remove the dependency on the GeoIP C API, but it appears that I was mistaken. Oh well.

Perhaps the biggest improvement in this new release is the use of caching. With caching in place, the middleware classes don't slam the database nearly as badly as they used to. There's still more that could be done with caching to improve performance, but I think what I've got now will be a big help.

Another noteworthy change, in my opinion, is the use of logging. I've sprinkled mildly useful logging messages throughout the code so you can learn when something bad happens that is silently handled. I hope that this will help me improve the quality of the code as it will allow anyone who uses the project (and pays attention to the log messages, of course) to tell me when bad things are happening.

Finally, the packaging code has been updated to be much more simple. Version 0.3.5 has been uploaded to PyPI and is available via pip or easy_install. If you prefer to have the latest copy of the code, the official code repositories are (in order of my personal preference):

• http://bitbucket.org/codekoala/django-tracking
• github.com/codekoala/django-tracking
• http://code.google.com/p/django-tracking

I can't wait for your feedback!

One of the tools I find myself using more and more each day is the amazing grep. It helps me narrow down the list of potential problem children in my code. Sometimes it can even tell me exactly where I need to look if my parameters are specific enough.

For example, the other day, I had a problem where some Python code was attempting to call isdigit() on an integer, when the variable was supposed to be a string. I could have scoured the code manually for all occurrences of the word "isdigit", or I could have used a "search in files" sort of feature in any useful text editor. There are likely other options too. However, I opted to use grep to find what I was looking for.

In the process of fixing this bug, I learned that grep offers the option of displaying a few lines of context around your matching text. There are a few ways you can tell grep to give you some context:

• -A NUM, --after-context=NUM

  Print NUM lines of trailing context after matching lines. Places a line containing -- between contiguous groups of matches.

• -B NUM, --before-context=NUM

  Print NUM lines of leading context before matching lines. Places a line containing -- between contiguous groups of matches.

• -C NUM, --context=NUM

  Print NUM lines of output context. Places a line containing -- between contiguous groups of matches.

I thought this was so useful that I wrote a small shell script to wrap up my common options for grepping--recursive search, display line numbers, and (now) showing some context. Eventually I got around to cleaning up the output by dirtying up the script. Cleaning up the output involved only displaying a matching filename one time, with the line numbers for the context and matching lines below it. I also thought it would be easier to find matching lines if I could colorize the matched text. Here's my script as of noon today.

#!/bin/bash
# Recursively greps for some text in files in the current directory with some
# context lines.

GREEN=`echo -e '\033[41;30;1m'`
NORMAL=`echo -e '\033[0m'`
FIND=$1
grep --exclude=*.svn* --exclude=*.swp -rnC 5 "$FIND" * | \
    awk '{split($1, a, "-"); split(a[1], b, ":"); \
    if (b[1] != file) { file=b[1]; print file; } \
    sub(file, "", $0); print $0; }' | \
    sed -e "s/$FIND/$GREEN&$NORMAL/g;s/^[-\:]//g"

I'm sure there are ways to make this more elegant, but I'm sure happy with it. This little dandy assisted me just this morning in helping a friend resolve some Django bugs!

Here's a screenshot:

With all of the exciting updates to Mercurial recently, I've been on a rampage, updating various boxes everywhere I go. I'm in the habit of using easy_install and/or pip to install most of my Python-related packages. It's pretty easy to install packages that are in well-known locations (like PyPI or on Google Code, for example). It's also pretty easy to update packages using either utility. Both take a -U parameter, which, to my knowledge, tells it to actually check for updates and install the latest version.

That's all fine and dandy, but what happens when you want to install an "unofficial" version of some package? I mean, what if your favorite project all of the sudden includes some feature that you will die unless you can have access to it and the next official version is weeks or months in the future? There are typically a few avenues you can take to satisfy your needs, but I wanted to bring up something that I think not many people are aware of: easy_install and pip can both understand URLs to installable Python packages.

What do I mean by that, you ask? Well, when you get down to the basics of what both utilities do, they just take care of downloading some Python package and installing it with the setup.py file contained therein. In many cases, these utilities will search various package repositories, such as PyPI, to download whatever package you specify. If the package is found, it will be downloaded and extracted.

In most cases, you can do all of that yourself:

$ wget http://pypi.python.org/someproject/somepackage.tar.gz
$ tar zxf somepackage.tar.gz
$ cd somepackage
$ python setup.py install

Both easy_install and pip obviously do a lot of other magic, but that is perhaps the most basic way to understand what they do. To answer that last question, you can help your utility of choice out by specifying the exact URL to the specific package you want it to install for you:

$ easy_install http://pypi.python.org/someproject/somepackage.tar.gz
$ pip install http://pypi.python.org/someproject/somepackage.tar.gz

For me, this feature comes in very handy with projects that are hosted on BitBucket, for example, because you can always get any revision of the project in a tidy .tar.gz file. So when I'm updating Mercurial installations, I can do this to get the latest stable revision:

$ easy_install http://selenic.com/repo/hg-stable/archive/tip.tar.gz

It's pretty slick. Here's a full example:

[user@web ~]$ hg version
Mercurial Distributed SCM (version 1.2.1)

Copyright (C) 2005-2009 Matt Mackall <mpm@selenic.com> and others
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
[user@web ~]$ easy_install http://selenic.com/repo/hg-stable/archive/tip.tar.gz
Downloading http://selenic.com/repo/hg-stable/archive/tip.tar.gz
Processing tip.tar.gz
Running Mercurial-stable-branch--8bce1e0d2801/setup.py -q bdist_egg --dist-dir /tmp/easy_install-Gnk2c9/Mercurial-stable-branch--8bce1e0d2801/egg-dist-tmp--2VAce
zip_safe flag not set; analyzing archive contents...
mercurial.help: module references __file__
mercurial.templater: module references __file__
mercurial.extensions: module references __file__
mercurial.i18n: module references __file__
mercurial.lsprof: module references __file__
Removing mercurial unknown from easy-install.pth file
Adding mercurial 1.4.1-4-8bce1e0d2801 to easy-install.pth file
Installing hg script to /home/user/bin

Installed /home/user/lib/python2.5/mercurial-1.4.1_4_8bce1e0d2801-py2.5-linux-i686.egg
Processing dependencies for mercurial==1.4.1-4-8bce1e0d2801
Finished processing dependencies for mercurial==1.4.1-4-8bce1e0d2801
[user@web ~]$ hg version
Mercurial Distributed SCM (version 1.4.1+4-8bce1e0d2801)

Copyright (C) 2005-2009 Matt Mackall <mpm@selenic.com> and others
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Notice the version change from 1.2.1 to 1.4.1+4-8bce1e0d2801. w00t.

Edit: devov pointed out that pip is capable of installing packages directly from its repository. I've never used this functionality, but I'm interested in trying it out sometime! Thanks devov!

I've done a lot of neat things since I started my new job earlier this month. I'm really excited about the things I've learned and experimented with, and I would like to share some of the concepts with my visitors.

At work we use a lot of virtual machines in our individual development environments. Most of these virtual machines use very similar configuration settings, but the settings are not a standard part of the installation. That is because we build our virtual machines using the same installation tools that our customers would use. The configuration I'm talking about is just stuff specific to our development environment.

Creating and configuring these virtual machines is one of the first things my mentor showed me how to do my first day on the job. He commented on how quickly I would probably start learning all of the configuration tasks because we tend to setup our development VMs several times a month. That was all fine and dandy, and I did get a pretty good feel for what needed to go into a development VM that first day.

However, after doing it so many times, I realized how much time I was using just trying to get the VM set up just right. It wasn't hard to configure--it was just time-consuming. It wasn't long before I started thinking of ways to optimize the process.

One of the ideas I came up with, which seems to be serving my purposes perfectly, is that of using Mercurial to quickly and easily get the exact same configuration from one box to another. It also has the added benefit of keeping a history of the changes I make to my configuration as time goes on.

I won't go into exact detail on how I have things setup at work, but I would like to try to describe a similar scenario that should illustrate my goal just as well.

cd /etc
hg init

hg st

hg add

hg ci -m "Initial import"

hg push ssh://root@slave1//etc
root@slave1's password:
remote: abort: There is no Mercurial repository here (.hg not found)!
abort: no suitable response from remote hg!

hg clone ssh://root@master//etc /etc
root@master's password:
abort: destination '/etc/' is not empty

scp -r root@master:/etc/.hg /etc/

hg st

hg clone http://bitbucket.org/codekoala/hgext /root/hgext
echo "[extensions]" >> /root/.hgrc
echo "neclone = /root/hgext/neclone.py" >> /root/.hgrc

hg neclone ssh://root@master//etc /etc
cd /etc
hg up -C

hg forget adjtime
hg forget mailcap

hg ci -Am "Removed some files from version control"

hg push
abort: repository default-push not found!

[paths]
default = ssh://root@master//etc

#!/bin/bash
hg up
for node in 'slave1' 'slave2'
do
    ssh root@$node "cd /etc; hg pull -u"
done

chmod +x /etc/propagate.sh

[hooks]
commit.propagate = /etc/propagate.sh
changegroup.propagate = /etc/propagate.sh

echo "" >> /etc/hosts
hg ci -m "Added a blank line to the hosts file"
root@slave1's password:
remote: Permission denied, please try again.
remote: Permission denied, please try again.
remote: Permission denied (publickey,password).
abort: no suitable response from remote hg!
Connection closed by slave2
warning: commit.propagate hook exited with status 255

ssh-keygen
cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys2
scp -r ~/.ssh root@slave1:~
scp -r ~/.ssh root@slave2:~

remote: Host key verification failed.
abort: no suitable response from remote hg!

10.0.0.5        nonexistanthost

hg ci -m "Added a dumb line to the hosts file"
hg push

remote: pulling from ssh://root@master//etc
remote: searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files

Some of you may well know that I was previously an subversion user, more out of comfort than necessity. SVN was the first version control system that I became well acquainted with, so it just seemed like a natural choice for me when I thought I needed version control.

Several months ago I read a blog article by a buddy, in which he briefly discussed Mercurial. I had been meaning to give some distributed version control systems a shot after some disasters related to the centralized nature of SVN. This blog article prompted me to take a stab at Mercurial and some others.

Within a few days I was sold on Mercurial. I won't go into details simply because I'm not one for religious wars that way. Let's just say that Mercurial seemed to be perfect for my wants and needs.

There were, however, a few things about using Mercurial that I miss from the SVN world. One such thing is that you can update several "working copies" of something in SVN with a single command. For example, I keep a lot of my 3rd party Django applications in one directory. Many of these applications use SVN. Sometimes I'll just run a command like this:

svn up /path/to/third/party/apps/*

Each project that uses SVN will automatically be updated without much fuss with such a command. However, with Mercurial, it appears that you need to be in an actual Mercurial repository in order to update it. There are extensions to get around this problem, but I was looking for something a little different.

Since I use Linux almost exclusively, I didn't feel bad about just using the power within to do the work. The following command does everything I need it to:

find -name ".hg" -type d | xargs -t -i bash -c "(cd {}; hg pull; hg up)"

This command finds any directories called .hg anywhere under your current location on the filesystem. Any matches will be used in the command at the end: cd {}; hg pull; hg up

So far I haven't had any problems with this command, but your mileage may vary. To make things even easier, I made an alias for this rather long command:

alias hgupall='find -name ".hg" -type d | xargs -t -i bash -c "(cd {}; hg pull; hg up)"'

I put that line in my ~/.bashrc script, which is executed each time I log into my computer. With that in place, all I need to do is something like this:

cd /path/to/third/party/apps
hgupall

And the aliased command handles the rest. Pretty slick stuff. Hooray for Mercurial and Linux!

Today marks the official release of Mercurial 1.3, an awesome distributed version control system. This release comes with several nifty features, including the following, straight from the What's New wiki page:

Along with my recent adventures with Fedora 11, I decided to force myself to become more proficient with VIM. For those of you who do not know, VIM is based on perhaps one of the oldest surviving text editors around today. There are often religious-grade battles between those who believe in VIM and those who believe in Emacs, another long-surviving text editor. I'm not trying to get into any debates about which is better, and I'm not interested in why I should not be using VIM. If you still feel like I need to be set straight, please use the contact me form instead of the comments section.

Anyway, most people who use these editors fall into 1 of 3 categories (there are probably more categories actually):

1. They're familiar with it enough to get the job done, but they're not exactly proficient. Therefore, they don't care about evangelizing the editor.
2. They're proficient with the editor, but they're afraid of the politics involved in religious wars relating to text editors, so they don't evangelize.
3. They're proficient with the editor and feel that the whole world would be better off if everyone used their preferred text editor. As such, they cannot shut up about the dang thing and drive all of their friends, coworkers, and acquaintances mad.

A few of you will probably agree with what I'm about to say. I fear I have transitioned from stage 1 to stage 3 fairly rapidly. I can't stop talking about VIM all of the sudden! You'd think it's the next best thing after sliced bread the way I've been blabbering about it. And here I am, writing an article about it. Hah.

Ever since I first started using Linux, I have been using vi to handle most of my text editing when I was in a terminal. I knew enough to get around. Basic things like navigation and inserting text were pretty much all I knew how to do. I dabbled with a tutorial here and there, but it wasn't long before the things I learned were lost, since I usually preferred a graphical text editor over VIM.

My recent experimentation with VIM has proved to be very fruitful, if I do say so myself. I am no longer tied down to some editor that is slow and bulky, I don't have much to worry about when I switch computers (chances are that VIM is on any computer I use regularly), and I don't even need to be sitting at the computer I'm using VIM on! In fact, today I was doing most of my work over an SSH session to my netbook. I felt more productive today than I have in a very long time.

It's been a long time since I've enjoyed using a mouse to perform basic tasks on my computer. Using VIM allows me to rid myself of the mouse entirely for my text editing tasks, and I don't feel at all limited in my capabilities. Things that used to be quite sketchy operations using my favorite graphical editors end up being very simple with VIM.

I also love the obscurity favor of it all.

Examples
========

<a href="http://www.somelong.com/that/I/want/to/change/">Link Text</a>

:s/something/lambda (a,b,c): \0(a,b,c)/g

:.,.+9 s/something/lambda (a,b,c): \0(a,b,c)/g