How to ignore “Unable to connect to target host” error messages

https://unix.stackexchange.com/questions/213326/how-to-ignore-unable-to-connect-to-target-host-error-messages/213422

-q      Quiet mode. 

未検証
http://man7.org/linux/man-pages/man5/ssh_config.5.html

LogLevel
Gives the verbosity level that is used when logging messages
from ssh(1). The possible values are: QUIET, FATAL, ERROR,
INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. The default
is INFO. DEBUG and DEBUG1 are equivalent. DEBUG2 and DEBUG3
each specify higher levels of verbose output.

ssh_config:
LogLevel QUIET

めも、未検証