Since you're using CentOS 5, the default package manager is yum, not apt-get. To install a program using it, you'd normally use the following command:
$ sudo yum install <packagename>
However, when trying to install git this way, you'll encounter the following error on CentOS 5:
| # First verify the version of Java being used is not SunJSK. | |
| java -version | |
| # Get the latest Sun Java SDK from Oracle http://www.oracle.com/technetwork/java/javase/downloads/jdk-7u1-download-513651.html | |
| wget http://download.oracle.com/otn-pub/java/jdk/7u1-b08/jdk-7u1-linux-i586.rpm | |
| # Rename the file downloaded, just to be nice | |
| mv jdk-7u1-linux-i586.rpm\?e\=1320265424\&h\=916f87354faed15fe652d9f76d64c844 jdk-7u1-linux-i586.rpm | |
| # Install Java |