Install Sun Java JDK in Ubuntu 10.10

To install Sun's Java 6 JDK on Ubuntu 10.10, add the Sun Java6 Community PPA and install:

sudo add-apt-repository ppa:sun-java-community-team/sun-java6
sudo apt-get update
sudo apt-get install sun-java6-jdk sun-java6-plugin
sudo update-java-alternatives -s java-6-sun

GRUB 2 Splash Images on Ubuntu

Here is how you can get a nice background image for GRUB boot menu.
First, install the "grub2-splashimages" package:

sudo apt-get install grub2-splashimages

Then edit /etc/default/grub and add the following line

GRUB_BACKGROUND=/usr/share/images/grub/yourImage.png

Also, make sure that GRUB is loaded in the same resolution as the image

GRUB_GFXMODE=1680x1050

...and that's it. Update GRUB

sudo update-grub

and restart to see the results.

How to delete all .svn directories

If you are using subversion, at some point you probably tried to take some folders from one repository and try to commit then to another. Since each folder has a hidden .svn folder, subversion will complain that "they are already under version control". Here is how to recursively delete all .svn folders:

find . -name ".svn" -type d -exec rm -rf {} \; -prune -print

Copy Paste between Emacs and other applications

If you are using GNU Emacs in an X-windows environment like Gnome, you would have noticed that sometimes copy-pasting from Emacs to other applications or vice versa does not work.
To fix this, edit your .emacs file (located in your home folder) and add the following lines:

;; Send primary selection to clipboard so copy-paste works with other X-applications
(global-set-key "\C-w" 'clipboard-kill-region)
(global-set-key "\M-w" 'clipboard-kill-ring-save)
(global-set-key "\C-y" 'clipboard-yank)

OpenCV 2.2 on Ubuntu 10.10

*Update: For OpenCV 2.4 on Ubuntu 12.04 see my latest post.

OpenCV (Open Source Computer Vision) is a library of programming functions for real time computer vision. It is released under a BSD license, it is free for both academic and commercial use. It has C++, C, Python and soon Java interfaces running on Windows, Linux, Android and Mac.

This is how to build and install OpenCV 2.2 on Ubuntu 10.10.

First, install the dependencies from the repositories:

sudo apt-get install build-essential libgtk2.0-dev libavcodec-dev libavformat-dev libjpeg62-dev libtiff4-dev cmake libswscale-dev libjasper-dev

Download the source code:

wget http://sourceforge.net/projects/opencvlibrary/files/opencv-unix/2.2/OpenCV-2.2.0.tar.bz2

Extract, create the build directory:

tar xfv OpenCV-2.2.0.tar.bz2
rm OpenCV-2.2.0.tar.bz2
cd OpenCV-2.2.0
mkdir opencv.build
cd opencv.build

Configure, make and install:

cmake ..
make
sudo make install

To configure the library, edit the following file (might be empty):

sudo gedit /etc/ld.so.conf.d/opencv.conf

and add the line

/usr/local/lib

Then run:

sudo ldconfig

Finally, edit the file:

sudo gedit /etc/bash.bashrc

and add the following lines at the end:

PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/local/lib/pkgconfig
export PKG_CONFIG_PATH

Most of the above was find here.

Older versions? Take a look at the following links:

OpenCV 2.1 on Ubuntu 10.04 (pretty much the same as above, but with TBB)
OpenCV 2.0 on Ubuntu 9.10

For OpenCV 2.3.1 see this post.

Completely Disable Touchpad in Ubuntu

To temporarily disable the touchpad while typing just go to
System > Preferences > Touchpad
and check
Disable touchpad while typing
but if you want to completely disable it, you can do the following
In a terminal type:

xinput list | grep -i touchpad

to determine the device ID (in my case, 14). Then disable by typing:

xinput set-prop 14 "Device Enabled" 0

To enable it, type:

xinput set-prop 14 "Device Enabled" 1

From the Ubuntu Documentation: Synaptics Touchpad

Ogre3D Applications and Emacs

This is the first application of the Ogre3D tutorial, set up for compiling by calling

make -k

from Emacs. This is useful when you have a shortcut for M-x compile say, F1, so you want to be able to call make from the directory where all your source files are located. The Makefile in the root directory just removes old cmake files, then runs cmake inside build directory and creates the Makefile to build the project. Then builds and executes.

• Cmake output is redirected to the file /build/cmake.output
• The executable (OgreApp) is located in build/dist/build
• The execution log is in build/dist/bin/OgreApp.log

Now you can edit the source files of your Ogre3D application, then hit F1 (or whatever key you've assigned compile to) and build/execute by just pressing one key.

You can download all files from here.