Starting ssh-agent in bash

ssh-agent.sh

## start ssh-agent
# see https://stackoverflow.com/questions/40549332/how-to-check-if-ssh-agent-is-already-running-in-bash
USER="${USER:-$(id -un)}" # fix for Windows git-bash which does not set the USER variable
export SSH_AUTH_SOCK=${SSH_AUTH_SOCK:-/tmp/ssh-agent-${USER}.sock}
agent_run_state=$(ssh-add -l > /dev/null 2>&1 ; echo $?)
# agent_run_state == 0    agent runs with keys
# agent_run_state == 1    agent runs without keys
# agent_run_state == 2    agent is not running
if [[ $agent_run_state = 2 ]]  ; then
	# Load stored agent connection info.
    [[ -r ~/.ssh-agent-${HOSTNAME} ]] && eval "$(<~/.ssh-agent-${HOSTNAME})" >/dev/null
	rm -f "$SSH_AUTH_SOCK"
	ssh-agent -a "$SSH_AUTH_SOCK" > ~/.ssh-agent-${HOSTNAME}
	eval "$(<~/.ssh-agent-${HOSTNAME})" >/dev/null
	echo "Running ssh-agent with PID ${SSH_AGENT_PID} on ${HOSTNAME}"
fi
if [[ $agent_run_state != 0 ]] ; then
    # do this individually for all keys you need to be added
	ssh-add $HOME/.ssh/id_ed25519_MYSERVER
fi