Redshift is an interesting program that adjusts the color temperature of your screen according to your surroundings.And the most important is this may help your eyes hurt less if you’re long time working in front of the screen,especially at night.
Redshift uses an X server extension to adjust the color temperature.A different color temperature is set during night and daytime.During the day, the color temperature should set to match the light from outside.At night the color temperature should be set to match the lamps in your room.

Install Redshift
To install Redshift,your graphics driver and X server needs to either support at least RANDR version 1.3 or the VidMode extension.

For Ubuntu 9.10
Add the PPA by typing this command in Applications->Accessories->Terminal:

sudo add-apt-repository ppa:jonls/redshift-ppa

then update system and install:

sudo apt-get update
sudo apt-get install redshift

Unfortunately,I can’t install this from PPA in my Ubuntu 10.04 beta2.So,I download the source code (redshift-1.2.tar.bz2) from:https://launchpad.net/redshift/+download and save it in Download/ folder.

navigate to the directory,unpack the package,and compile:

cd Downloads/
tar jvxf redshift-1.2.tar.bz2
cd redshift-1.2/
./configure
make
make install

You can read INSTALL file in redshift-1.2/ folder to get more installation instructions.
The homepage of Redshift is:http://jonls.dk/redshift/