Use of ssh-agent

The problem with using ssh-agent today is that I have to enter passphrase on the sshcodegerrit machine on the qa machine. Passphrase is required without entering the password, indicating that the trust relationship has been established, but the key is not added to the ssh-agent. Why does www.2cto.com encounter the problem of using sh... ssh-agent every time today? I need to enter passphrase on the qa machine ssh code gerrit machine.
Passphrase is required without entering the password, indicating that the trust relationship has been established,
But the key is not added to the ssh-agent. How does www.2cto.com add the key to the ssh-agent every time the shell is started?

You can add it to/etc/profile. d. However, you still need to enter
One passphrase.

You only need to set an empty passpharse. Ssh-agent also has a proxy forwarding function that can be used in multiple consecutive ssh
The previous ssh-agent does not have to save the private key in multiple places. Reference: http://www.2cto.com/ OS /201303/195006.html