ssh-agent start up scritp

To activate ssh-agent when login, I put some scripts in my bash profile.

=> .bash_profile

#-------------------------------------------------------------------
SSH_ENV=${HOME}/.ssh/environment

function start_agent {
       echo -n "Initialising new SSH agent..."
       sleep 1
       ssh-agent | sed 's/^echo/#echo/' > ${SSH_ENV}
       echo "succeeded!"
       source ${SSH_ENV}
       ssh-add;
}

# Source SSH settings, if applicable
if [ -f "${SSH_ENV}" ]; then
       source ${SSH_ENV}
       #ps ${SSH_AGENT_PID} doesn't work under cygwin
       ( ps -ef | grep ${SSH_AGENT_PID} \
     && ps ux| grep ${SSH_AGENT_PID} ) \
     > /dev/null || {
               start_agent
       }
else
       start_agent
fi

=> .bash_logout

#-------------------------------------------------------------------
function quit_agent {
   echo -n "Cleaning ssh-agent settins..."
   sleep 1

   ssh-add -D
   ssh-agent -k > /dev/null 2>&1
   unset SSH_AGENT_PID
   unset SSH_AUTH_SOCK
   echo "succeeded!"
   sleep 1
}

if [ ${SSH_AGENT_PID+1}  == 1 ]; then
   echo -n "Quit ssh-agent? (No or Yes) "
   while [ 1 ]; do
       read ANS
       case ${ANS} in
           [Yy][Ee][Ss]|[Yy])
               quit_agent
               exit
               ;;
           [Nn][Oo]|[Nn])
               echo "ssh-agent will continue to serve!"
               sleep 2
               exit
               ;;
           *)
               echo -n "What do you mean? (No or Yes)"
               ;;
       esac
   done
fi