The situation:

• I have an IP : 192.168.1.1 $IP
• username : root (or whatever) $USER
• and a passwd: foo $PASSWD

Is there a way to give $PASSWD to ssh ? like

 PASSWORD_VAR=$PASSWD ssh -l $USER $IP

• user can see the password,
• user must "land" on usual interactive shell session.
• somme package might be installed on desktop linux if need be.

reading ssh(1) give me no clues. such thing exists in window's world (e.g. Kitty), now I would like to do the same in unix (suse or unbuntu if that matter).

I know how to set up public/private key pair, but this is off topic.