Use basic Linux utilities to list file names and their contents.
Pretty print size in bytes using AWK.
Use simple shell function to instantly create known_hosts entries for specified host, including its IP address and remove outdated public host keys.
known_hosts file located in
/etc/ssh/ssh_known_hosts and user managed
~/.ssh/known_hosts contains known host public keys. Due to its nature these files can contain multiple entries using the same key. It is not a problem, but merging entries using the same key is the first step that is necessary to inspect it visually and to verify host entries.