ssh key add

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# SSH - Windows
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

# Start the SSH agent and init temp $env
env=~/.ssh/agent.env

agent_load_env () { test -f "$env" && . "$env" >| /dev/null ; }

agent_start () {
    (umask 077; ssh-agent >| "$env")
    . "$env" >| /dev/null; }

# Get your agent running and add your new key
if [ ! "$SSH_AUTH_SOCK" ] || [ $agent_run_state = 2 ]; then
    agent_start
    ssh-add
    ssh-add <YOUR NEW KEY>
elif [ "$SSH_AUTH_SOCK" ] && [ $agent_run_state = 1 ]; then
    ssh-add
    ssh-add <YOUR NEW KEY>
fi

# Delete the temp $env
unset env

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# SSH - Macintosh
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

# Get your agent running and add your new key
# If working with zShell, add `-z` before "$SSH_AUTH_SOCK" 
# IE: if [ ! -z "$SSH_AUTH_SOCK" ] || [ $agent_run_state = 2 ]; then
if [ ! -z "$SSH_AUTH_SOCK" ] || [ $agent_run_state = 2 ]; then
    ssh-add
    ssh-add <YOUR NEW KEY>
elif [ -z "$SSH_AUTH_SOCK" ] && [ $agent_run_state = 1 ]; then
    ssh-add
    ssh-add <YOUR NEW KEY>
fi

# Delete the temp $env
unset env