keychain is a manager for the SSH agent. It ensures that there is a single running SSH agent which can be used from several shells at the same time.

The standard usage of keychain in a bash is demonstrated by the following listing:

$ keychain
$ source ~/.keychain/$(uname -n)-sh

A similar behaviour has previously been implemented by myself, see my setup and my setup 2.

Feedback is always welcome! If you'd like to get in touch with me concerning the contents of this article, please use Twitter.