startSSHAgent bash function - checks for SSH_AGENT_PID in env, then for ssh-agent PID (pgrep), if not found, starts new ssh-agent, adds your keys

startSSHAgent.sh

startSSHAgent() {
  if [[ -z "$SSH_AGENT_PID" ]]; then
      if [[ $(pgrep ssh-agent) ]]; then
          export SSH_AGENT_PID=$(pgrep ssh-agent)
          echo "Found existing ssh-agent PID, SSH_AGENT_PID=${SSH_AGENT_PID}"
      else
        echo "Starting fresh ssh agent"
        eval `ssh-agent`
      fi
  fi
  
  ssh-add ~/.ssh/my-private-key1
  ssh-add ~/.ssh/my-private-key2
  #...
  ssh-add ~/.ssh/my-private-keyN
  kill_old_ssh_agents #see https://gist.github.com/gubatron/2d97b31b0621c459f8b5ee8665c9f7b9
}

Hi guba! Miss your patches at Flowee.org :)

The umask is probably not really needed, it was to make sure that the file is only readable by owner.

the limit of 48 hours is not on the life of the agent, it is on how long the agent keeps passwords. So you'd have to do a 'ssh-add' again after that. It is purely for security.

I just eval the output

That has the downside that if you logout your ssh-agent will keep running but you can't reach it anymore. Next time you login another agent will start. And you'll end up with more and more of them.
My writing file solution also means that if I login on the desktop and then later ssh to the same machine then I can reuse the already running ssh agent.

well I only eval if I can't find an existing ssh-agent, otherwise yes you end up with a bunch of ssh-agent processes

Ill check what's up with flowee.org and how I can help once I get a breather