The command ‘/usr/bin/unhide.rb’ has been replaced by a script

You can get this issue with rkhunter :

Warning: The command '/usr/bin/unhide.rb' has been replaced by a script: /usr/bin/unhide.rb: Ruby script

You have to edit the rkhunter configuration file :

nano /etc/rkhunter.conf

And add :

SCRIPTWHITELIST=/usr/bin/unhide.rb

Just after the other SCRIPTWHITELIST lines.