SSH_ASKPASS

$ man ssh

...

SSH_ASKPASS

If ssh needs a passphrase, it will read the

passphrase from the current terminal if it was run

from a terminal. If ssh does not have a terminal

associated with it but DISPLAY and SSH_ASKPASS are

set, it will execute the program specified by

SSH_ASKPASS and open an X11 window to read the

passphrase. This is particularly useful when call‐

ing ssh from a .xsession or related script. (Note

that on some machines it may be necessary to redi‐

rect the input from /dev/null to make this work.)

...

Keep in mind that ssh stands for secure shell, and if you store your user, host and password in plain text files you are misleading the tool an creating a possible security gap

$ cat ~/echo_pass

echo toor

$

$ cat ssh_session

export SSH_ASKPASS='~/echo_pass'

setsid ssh root@127.0.0.1

$ chmod u+x echo_pass

$ chmod u+x ssh_session

 ./ssh_session

$ ./ssh_session

Welcome to Ubuntu 18.04.5 LTS (GNU/Linux 4.15.0-121-generic x86_64)

operator@server:~$

https://stackoverflow.com/questions/1340366/how-to-make-ssh-receive-the-password-from-stdin