Users (Owners)

find / -a -user [username]	Owned by user
find / -a ! -user [username]	Not owned by user
find / -a -group [groupname]	Group name
find / -a -user "root:developers"	Owned by root AND belong to developers group
find / -a -user root -o -group root	Owned by root OR belong to root group
find / -a -user1 [username1] -o -user2 [username2]	Multiple owners (username1 OR username2)
find / -a -user "([username1]|[username2])"	Multiple owners (username1 OR username2)
find / -a -nouser -exec ls -l {} \;	No owner
find / -a -nogroup -exec ls -l {} \;	No group
sudo -u [username] find / -user [username]	Executes find as <username>

Recursively lists file ACLs and filters for entries related to [username]. This can be useful for systems using ACLs for finer-grained permissions:

getfacl -R [directory] | grep "user:[username]"

Lists files and directories in [directory] with detailed information and filters the output for those owned by [username].

Note: This method is less reliable and more cumbersome than using find. This is more of a last resort option:

` ls -l [directory] | grep '^.\{8\}[username]'