How to get "Enter passphrase" on command line rather than GUI pop-up?

[Chris Green]

> 
> There must be *something* in the environment that affects this because
> I'm seeing two different ways of asking for the passphrase on the same
> screen.  The only difference is that one is a simple terminal window
> running on my system and the other is one where I have used ssh to
> connect to a remote system and then ssh again back to the 'home'
> system.  The local system window gets the GUI pop-up the 'two ssh'
> window asks for the passphrase in the terminal.
> 
I think I have it! I need to unset SSH_AUTH_SOCK, that's all that's
needed.  See:-

    chris$ ssh -i backup_id_rsa backup
[here the pop-up appears and I cancel it]
    sign_and_send_pubkey: signing failed for RSA "backup_id_rsa" from
    agent: agent refused operation
    chris at backup's password: 

    chris$ env | grep SSH
    SSH_AUTH_SOCK=/run/user/1000/keyring/ssh
    SSH_ASKPASS_REQUIRE=never
    chris$ unset SSH_AUTH_SOCK
    chris$ ssh -i backup_id_rsa backup
    Enter passphrase for key 'backup_id_rsa': 
    chris at backup$ 

So the SSH_ASKPASS etc. are irrelevant for my set-up.  I thought I'd
tried unsetting SSH_AUTH_SOCK before but obviously I hadn't, I guess
the need to specify the key file is a result of not having that but
it's not a problem for me really.

-- 
Chris Green