So long, farewell, and thanks for all the fish!

#include <stdio.h>

int main(void)
{
    printf("Goodbye world... :( \n");

    return 70;
}

HOWTO Remove the annoying floating ads from Gmail's Preview Theme

Problem

Gmail's Preview Theme without floating ads.

You switched your Gmail theme, and you find the floating advertisement annoying.

Solution (for Chrome)
Modify Gmail's stylesheet to prevent the ads from floating.

1. Install the Personalized Web Chrome extension.
2. Go to Tools -> Extensions.
3. Find the Personalized Web section and click "Options".
4. Click "Add New Rule".
5. In the "Match URLs" textbox, input "mail.google.com".
6. In the "Add CSS" textbox, input:
.mq {
    position: relative;
    bottom: 0px;
    left: 0px;
    margin: 0px;
}

7. Click "Save".

Reload Gmail to see the effect.

FAQ
Q: Why not just disable the advertisement in the first place?
A: Nothing in life is free; Google is providing us with this free service in exchange for displaying ads.  It's a fair deal.

Q: Does this work on Firefox?
A: No, but you can just google for steps on using a custom CSS.  You may use the same CSS from Step 6.

Required packages for building an Android OS on Ubuntu

Problem
You're trying to install the required packages for building a complete Android Operating System from scratch. Upon pasting the commands from the official documentation, you get the following error:

E: Couldn't find package lib32ncurses5-dev
E: Couldn't find package lib32readline5-dev
E: Couldn't find package lib32z-dev
E: Couldn't find package mingw32


Solution
The list of required packages for building an Android OS is wrong. The correct packages are:

sudo apt-get install git-core gnupg flex bison gperf build-essential \
zip curl zlib1g-dev libc6-dev lib64ncurses5-dev \
x11proto-core-dev libx11-dev lib64readline5-dev lib64z-dev \
libgl1-mesa-dev g++-multilib tofrodos


Note: This has been tested on Ubuntu 10.04 (Lucid Lynx). YMMV.

Downgrading from PHP 5.3 to 5.2 on Debian Squeeze

Problem

You've installed PHP 5.3 on your Debian Squeeze system. Problem is, some web apps have trouble running on that version. You need to downgrade your system from 5.3 to 5.2.

Solution

Remove the PHP 5.3 packages from your system:

sudo aptitude purge `dpkg -l | grep php| awk '{print $2}' |tr "\n" " "`

Clean the cache just to be sure:

rm -f /var/cache/apt/archives/php5*

Use Karmiс for PHP packages:

echo -e "Package: php5\nPin: release v=karmic\nPin-Priority: 991\n" | sudo tee /etc/apt/preferences.d/php > /dev/null
apt-cache search php5-|grep php5-|awk '{print "Package:", $1,"\nPin: release v=karmic\nPin-Priority: 991\n"}'|sudo tee /etc/apt/preferences.d/php > /dev/null

Add Ubuntu Karmic to source list:

cd /etc/apt/sources.list.d
sudo wget -O karmic.list "http://pastebin.com/download.php?i=q9ya307g"

(Update, October 18, 2012: The sources list has been updated, because Ubuntu no longer supports Karmic. Please leave a comment if this still doesn't work.)

Update the package database:

sudo apt-get update

If the command above produces this error:

W: GPG error: http://security.ubuntu.com karmic-security Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5
W: GPG error: http://archive.ubuntu.com karmic Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5
W: GPG error: http://archive.ubuntu.com karmic-updates Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5

Then import the required keys and add them to your list of trusted keys:

gpg --keyserver hkp://subkeys.pgp.net --recv-keys 40976EAF437D05B5
gpg --export --armor 437D05B5 | sudo apt-key add -

gpg --keyserver hkp://subkeys.pgp.net --recv-keys 40976EAF437D05B5
gpg --export --armor 40976EAF437D05B5 | sudo apt-key add -

gpg --keyserver hkp://subkeys.pgp.net --recv-keys 40976EAF437D05B5
gpg --export --armor 40976EAF437D05B5 | sudo apt-key add -

Finally, install PHP 5.2:

sudo apt-get install -t karmic php5-cli php5-cgi libapache2-mod-php5

UPDATE: Using the Ubuntu sources to download old packages works on Debian. So far, it works on my system, but you may need to use the Debian sources just in case.