auto-start ssh-agent on login

auto-start ssh-agent

############ FROM http://rocksolidwebdesign.com/notes-and-fixes/ubuntu-server-ssh-agent/ ###########
# Check to see if SSH Agent is already running
agent_pid="$(ps -ef | grep "ssh-agent" | grep -v "grep" | awk '{print($2)}')"

# If the agent is not running (pid is zero length string)
if [[ -z "$agent_pid" ]]; then
    # Start up SSH Agent
    # this seems to be the proper method as opposed to `exec ssh-agent bash`
    eval "$(ssh-agent)"

# If the agent is running (pid is non zero)
else
    # Connect to the currently running ssh-agent
    agent_ppid="$(($agent_pid - 1))"

    # and the actual auth socket file name is simply numerically one less than
    # the actual process id, regardless of what `ps -ef` reports as the ppid
    agent_sock="$(find /tmp -path "*ssh*" -type s -iname "agent.$agent_ppid")"

    echo "Agent pid $agent_pid"
    export SSH_AGENT_PID="$agent_pid"

    echo "Agent sock $agent_sock"
    export SSH_AUTH_SOCK="$agent_sock"
fi
################ END SSH AGENT SCRIPT #################

In my case, the ppid is not the pid minus one, but the ppid can be obtained in the same manner as the pid is found except getting the third element instead of the second.