For installing cmake-2.8.3 following the steps below:

1- Download cmake-2.8.3: Run command below:

  $ wget http://www.cmake.org/files/v2.8/cmake-2.8.3.tar.gz

2- unzipping file that you downloaded it:Run command below:

  $ tar xzf cmake-2.8.3.tar.gz

3- run the following code:

   $ cd cmake-2.8.3

4- make a Configuration:Run command below:

    $ ./configure --prefix=/opt/cmake

5- install script to install CMake:

     $ make

6- complete the Installation:Run command below:

       $ make install

7- for install verification run command below:

       $ /opt/cmake/bin/cmake -version

if anythings were OK you will see the script below:

    cmake version 2.8.3