How do I check if a package is available for install?

I have installed Ubuntu 12.04 LTS on Amazon EC2 instance along with Tomcat and MySql. Tomcat, Java and MySql packages were available along with Ubuntu and I didn't have to download them.

Now I wish to install Percona Xtrabackup to my Server.

Now, how do I find if a certain package is already available with the installation or I have to install it externally?


apt-cache search <name>

Will give you a list of available packages matching the name.