Start ssh agent if not running and save environment variable to share the agent across shell. Useful on Windows.

start_ssh_agent_if_not_running.sh

start_ssh_agent_if_not_running () {
        local SSH_ENVIRONMENT_FILE=~/.ssh/environment

        if [ -f "$SSH_ENVIRONMENT_FILE" ]; then
                source "$SSH_ENVIRONMENT_FILE"
        fi

        echo SSH_AGENT_PID='"'${SSH_AGENT_PID}'"'
        if [ ! -z ${SSH_AGENT_PID} ] && ps -p ${SSH_AGENT_PID} > /dev/null
        then
                echo "ssh agent already running"
        else
                echo "starting ssh agent..."
                ssh-agent -s > "${SSH_ENVIRONMENT_FILE}"
                cat "${SSH_ENVIRONMENT_FILE}"
        fi

        if [ -f "$SSH_ENVIRONMENT_FILE" ]; then
                source "${SSH_ENVIRONMENT_FILE}"
        fi
}

start_ssh_agent_if_not_running