Start and Stop ssh-agent

Below is the bash script used to start and stop ss-agent

#!/bin/bash

## in .bash_profile

SSHAGENT=`which ssh-agent`
SSHAGENTARGS="-s"
if [ -z "$SSH_AUTH_SOCK" -a -x "$SSHAGENT" ]; then
    eval `$SSHAGENT $SSHAGENTARGS`
    trap "kill $SSH_AGENT_PID" 0
fi

## in .logout

if [ ${SSH_AGENT_PID+1} == 1 ]; then
    ssh-add -D
    ssh-agent -k > /dev/null 2>&1
    unset SSH_AGENT_PID
    unset SSH_AUTH_SOCK
fi