Alternative to killing ssh-agent in ~/.bash_logout

etc-profile.d-ssh-agent.sh

# prevent leaked/orphaned ssh-agent processes
if [ -z "$SSH_AUTH_SOCK" ]; then
    eval "`ssh-agent`" >/dev/null
    ssh-add 2>/dev/null

    # create pipe handle to share across all processes
    coproc (
        read s # to avoid race condition do not die until we disown/do stuff with $COPROC
        # detach from tty
        setsid sh -c "
            trap '' HUP   # although we are detached, parent bash may still HUP us
            read s        # wait pipe EOF
            ssh-agent -k  # kill agent
        " <&0 &           # create grandchild and die
    ) >/dev/null 2>&1

    disown

    export _SSH_AGENT_HANDLE=${COPROC[1]}

    # clear FD_CLOEXEC for write side of the pipe and unblock the child
    eval "exec ${COPROC[0]}>&-; exec ${COPROC[0]}>&1 1>&${COPROC[1]} ${COPROC[1]}>&-; exec ${COPROC[1]}>&1 1>&${COPROC[0]} ${COPROC[0]}>&-; echo >&${COPROC[1]}"  
fi