How-to avoid ssh prompt for password

Sometimes, we don’t want to use password authentication when using ssh. For example, I wrapped ssh in my script. I want to it always uses key authentication. If there is no key setup, just exit.

I googled it. Most of them are given the option “PasswordAuthentication no”. But in my test, it didn’t work somehow (probably add it the ssh config file will work, but that’s not what I want):

 ssh dbox036 date
The authenticity of host 'dbox036(10.1.1.1)' can't be established.
RSA key fingerprint is 50:ca:af:6c:27:b3:8d:74:e7:27:97:46:36:43:67:78.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'dbox036,10.1.1.1' (RSA) to the list of known hosts.
oracle@dbox036's password: 
Permission denied, please try again.
oracle@dbox036's password: 

I read ssh document and found parameter “NumberOfPasswordPrompts” can be used:

$ ssh  -o "NumberOfPasswordPrompts 0" dbox036
Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).

If you want to avoid the host key checking, add option “StrictHostKeyChecking no”

$ ssh -o "StrictHostKeyChecking no" -o "NumberOfPasswordPrompts 0" dbox036
Warning: Permanently added 'dbox036,10.1.1.1' (RSA) to the list of known hosts.
Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).

If you want to avoid the “Warning” message, add option “LogLevel=quiet”, you will get nothing if it didn’t work

$ ssh -o "StrictHostKeyChecking no" -o "NumberOfPasswordPrompts 0"  -o LogLevel=quiet dbox039 date
$