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I recently setup openssh so I could use it with git.

In the process of setting it up (as per this article) I ran the commands:

$ eval "$(ssh-agent -s)"
$ ssh-add ~/.ssh/<name of key>

Some time later, after I logged out and back in I tried to use git push I got an error. The solution to this error was running those same commands again.

Please tell me how I can

  • Keep the ssh-agent running so I don't have to start a new one
  • Remember the keys I've added so I don't have to add them everytime

Just to clarify, I use zsh so certain bash features won't work in my .zshrc.

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3
  • You should start with understanding what is ssh-agent for and how does it work before trying to suit it your twisted use case.
    – Jakuje
    Dec 4, 2016 at 18:55
  • What error you got?
    – Jakuje
    Dec 4, 2016 at 19:05
  • @Jakuje The error was about a missing pubkey and asked "Have you started ssh-agent?".
    – timotree
    Dec 4, 2016 at 19:28

2 Answers 2

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What is ssh-agent for and how does it work?

The ssh-agent keeps your decrypted keys securely in memory and in your session. There is no reasonable and safe way to preserve the decrypted keys among reboots/re-logins.

OK, how can I automate it?

Automate ssh-agent startup

Add 

[ -z "$SSH_AUTH_SOCK" ] && eval "$(ssh-agent -s)"

to your ~/.bashrc or other startup script (~/.zshrc).

Automate adding the keys

The keys can be automatically added upon the first usage, when you add

AddKeysToAgent yes

to your ~/.ssh/config.

For more information on ~/.ssh/config see man ssh_config.

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9
  • So you're saying if I enable AddKeysToAgent, then whenever I type eval "$(ssh-agent -s)" it will add my key?
    – timotree
    Dec 4, 2016 at 19:27
  • If the agent is running and your ssh supports this option, then yes.
    – Jakuje
    Dec 4, 2016 at 19:28
  • Can you please clarify how I would automate starting the ssh-agent then?
    – timotree
    Dec 4, 2016 at 19:30
  • Basically, as explained in the other answer. [ -z "$SSH_AUTH_SOCK" ] && eval $(ssh-agent)
    – Jakuje
    Dec 4, 2016 at 19:31
  • 1
    On Ubuntu 19.10, I ended up with two instances of ssh-agent, as it appears to come preinstalled (?) - you can check with ps -e | grep 'ssh' to see if it's running. I only needed to add the the AddKeysToAgent yes setting to .ssh/config to make added keys persist between reboots.
    – mindplay.dk
    Feb 7, 2020 at 13:46
11

Add this to ~/.bashrc

This means ssh-agent will be started automatically when you open another session no your terminal

if [ -z "$SSH_AUTH_SOCK" ] ; then
 eval `ssh-agent -s`
fi

if you need a key to be added to the agent also add this

if [ -z "$SSH_AUTH_SOCK" ] ; then
 eval `ssh-agent -s`
 ssh-add ~/.ssh/<your private ssh key>
fi
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  • 3
    This was a good answer but doesn't explain what the command does.
    – timotree
    Dec 4, 2016 at 21:48
  • How can we persist passphrase?
    – HalfWebDev
    Mar 16, 2022 at 10:46
  • this is critical for AWS EC2 if custom keys are needed
    – Adam Bubela
    Nov 22, 2022 at 9:10

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