easily re-use ssh-agent session

ssh-start

#!/bin/bash

# agent file
agentFile="$HOME/ssh-agent.txt"

function getCurrentKey {
    # current key
    currentKey=$(ssh-add -l)
    errorCode=$?

    echo Status=$errorCode
    echo $currentKey

    return $errorCode
}

function addKey {
    # if no key then exit
    [[ ! -f "$HOME/.ssh/id_rsa" ]] && echo "Error: id_rsa not exists." && exit
    # new agent
    ssh-agent -s > $agentFile
    # load agent to current context
    source $agentFile
    # add the key to current agent
    ssh-add
}

function connect {
    # if pre-defined
    [[ "$1" == "" ]] && con="-p 2222 lesca@localhost"
    # else use $1
    [[ "$con" == "" ]] && con=$1
    # connect
    echo "Connecting to host - $con"
    ssh $con
    exit
}

function clean {
    echo "Cleaning cached keys ..."
    killall ssh-agent 2> /dev/null
    rm -f $agentFile
    exit
}

# clean
[[ "$1" == "clean" ]] && clean 

# get current key
echo "Looking for key from memory ..."
getCurrentKey
errorCode=$?

[[ "$errorCode" == "0" ]] && connect $1 
[[ "$errorCode" != "0" ]] && ssh-agent -k 2> /dev/null
[[ "$errorCode" != "0" ]] && [[ -f "$agentFile" ]] && echo "Reusing agent file ..." && source $agentFile 


# check key again
echo "Looking for key from agent file ..."
getCurrentKey
errorCode=$?

[[ "$errorCode" == "0" ]] && connect $1 
[[ "$errorCode" != "0" ]] && ssh-agent -k 2> /dev/null
[[ "$errorCode" != "0" ]] && echo "Addding key ..." && addKey 

# check key again
echo "Looking for just added key ..."
getCurrentKey
errorCode=$?

[[ "$errorCode" == "0" ]] && connect $1 
[[ "$errorCode" != "0" ]] && ssh-agent -k 2> /dev/null
[[ "$errorCode" != "0" ]] && echo "Failed adding key ..."