ssh-keygen without passphrase code example

Example 1: ssh agent remember passphrase

$ ssh-add -l

Example 2: ssh agent remember passphrase

$ ssh-agent 
SSH_AUTH_SOCK=/tmp/ssh-hZQhwQlxahPX/agent.1833; export SSH_AUTH_SOCK; 
SSH_AGENT_PID=1834; export SSH_AGENT_PID; 
echo Agent pid 496;