Usually, when using Subversion’s SSH authentication facility, Subversion’s client will make use of your own SSH-generated key-pair and read it from the proper location, usually $HOME/.ssh. However, there could be situations when you’ll need to use a different key-pair. In such situations you can use a nice trick to have svn+ssh authentication work smoothly.
Let’s say you have an external key-pair, the public key is already configured on the Subversion server. You have the private key stored somewhere in your home directory. Now when issuing a svn checkout you’ll find that you will need some sort of SSH’s -i parameter to tell svn to use your external key-pair for authentication. Since there is not way to instruct Subversion’s client to do so, you’ll need to use a system environment variable.
Subversion makes your life easier by providing the $SVN_SSH environment variable. This variable allows you to put the ssh command and modifiers that fit your authentication needs. For our external key-pair use case, you can do something like:
export SVN_SSH="ssh -i </path/to/external-key>"
Now, next time you use Subversion svn+ssh authentication facility, the client will read $SVN_SSH and instance a ssh tunnel using the parameters you have defined. Once it has successfully authenticated you can use Subversion commands such as checkout, commit, etc in the same fashion you would normally do.
svn co svn+ssh://[email protected]/repo/for/software
Alternatives
Jeff Epler offered great advice with a more flexible approach using .ssh/config and key-pairs based on hostname.
Host svn.example.com IdentityFile %d/.ssh/id_rsa-svn.example.com Host svn2.coder.com IdentityFile %d/.ssh/id_rsa-svn2.coder.com