Start SSH agent at login

start-ssh-agent.sh

#!/usr/bin/env bash

# Write paths to keys to autoload in ~/.autoload-ssh-keys

env=~/.ssh/agent.env
autoload=~/.autoload-ssh-keys

agent_load_env () { test -f "$env" && . "$env" >| /dev/null ; }

agent_start () {
  (umask 077; ssh-agent >| "$env")
  . "$env" >| /dev/null ; }

test -f "$autoload" && readarray -t keys <~/.autoload-ssh-keys

agent_load_env

# agent_run_state: 0=agent running w/ key; 1=agent w/o key; 2= agent not running
agent_run_state=$(ssh-add -l >| /dev/null 2>&1; echo $?)

if [ ! "$SSH_AUTH_SOCK" ] || [ $agent_run_state = 2 ]; then
  agent_start
  ssh-add "${keys[@]}"
elif [ "$SSH_AUTH_SOCK" ] && [ $agent_run_state = 1 ]; then
  ssh-add
  ssh-add "${keys[@]}"
fi

unset env