Update: March 9, 2010
Somehow I failed to notice that since 10.5 ssh agent is automatically started by OS X. My script just duplicated work that was already built-in to the OS.
To add a passphrase for a private key just type:
After this, ssh-agent is started automatically whenever ssh needs it. No extra work needed.
Comments
I found that the "sudo touch
I found that the "sudo touch /var/db/useLS" command given at http://www-uxsup.csx.cam.ac.uk/~aia21/osx/leopard-ssh.html with a reboot worked for me. The site says that you don't need the touch with Leopard, but with Snow Leopard it didn't work for me until I did it. HTH
You can also make a shell
You can also make a shell alias which adds your key to ssh-agent when ssh is called. I find this preferable to storing your private key password in the Keychain. I use tcsh, so this alias does the trick:
alias ssh 'if (`ssh-add -l` == "The agent has no identities.") ssh-add; /usr/bin/ssh'