# test -r ${HOME}/.ssh/setup_agent.sh && . ${HOME}/.ssh/setup_agent.sh
SSH_ENVFILE=${SSH_ENVFILE:-"/tmp/${USER}.ssh_env"}
SSH_AGENT=${SSH_AGENT:-"ssh-agent"}

start_agent() {
    touch "${SSH_ENVFILE}"
    chmod 600 "${SSH_ENVFILE}"
    ${SSH_AGENT} | sed 's/^echo/#echo/' > "${SSH_ENVFILE}"
    . "${SSH_ENVFILE}"
}
use_old_agent() {
    test -n "${SSH_AUTH_SOCK}" \
	-a -S "${SSH_AUTH_SOCK}" \
	-a -n "${SSH_CONNECTION}" || \
    { test -f "${SSH_ENVFILE}" \
	&& . "${SSH_ENVFILE}" \
	&& ps -ef | grep "${SSH_AGENT_PID}" | grep ssh-agent$ > /dev/null; }
}

{ use_old_agent || start_agent; } && echo "SSH agent: $SSH_AGENT_PID" 1>&2