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I have an Ubuntu Server 10.04 installation on Linode. I am trying to use ssh-agent to stop typing my passphrase everytime I need to push some changes to GitHub. I am using the script provided by GitHub here. But when I source my .zshrc file or when I logout and log back in I get the following error message:

Could not open a connection to your authentication agent.
Error: Can't open display: (null)

Does anyone know what the the problem might be and how I could fix it please?

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There's something wrong in your .zshrc. Line 47, I think (unless my crystal ball's gone misaligned again). Post your .zshrc, and try adding set -x at the beginning to see a trace of what it's doing. – Gilles Feb 28 '11 at 22:25
here is my .zshrc: pastie.org/1621083 – Robert Audi Mar 1 '11 at 15:51

Your .zshrc may be modifying the DISPLAY variable, or modifying access to the screen. Normally ssh-agent is started when you start gnome. The variable SSH_AUTH_SOCK is set to the socket of your ssh-agent. If this variable is set, then ssh-agent will try to open window to get the password for your key when it is needed.

If your display is not accessible you can use ssh-add to add the key from the command line. Do this after you reboot. You also need to repeat this if your key ages out.

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Thanks for your answer. It solves one part of the problem, which is that the second error message (Error: Can't open display: (null)) is unrelated to ssh-agent. It's related to oh-my-zsh. On the other hand, still don't know why ssh-agent fails (and why I get the first error message), but it might also be because of oh-my-zsh. – Robert Audi Feb 28 '11 at 7:15

Sounds like ssh-agent is not running when you source the file. You have lines 46 and 47 commented out:

# eval `ssh-agent`
# ssh-add ~/.ssh/id_rsa

Try uncommenting those lines.

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