Starting ssh-agent just once (like on windows) wherever something isn't starting it for you

.bash_sshagent

#!/bin/bash
#
## Auto launch of ssh-agent from 
# https://help.github.com/articles/working-with-ssh-key-passphrases/#auto-launching-ssh-agent-on-git-for-windows

env=~/.ssh/agent.env

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

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

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
fi
unset env

# Now you still have to ssh-add

add_to_.profile

export PATH=~/bin:$PATH

. ~/.bash_sshagent