Not everybody uses POSIX ACLs on Linux. In fact, most users olympically ignore them, even when they're aware of what they are and what they do. But most distributions come with support for them. Some leave them enabled for the default filesystems; some don't.
My question is, is there an efficient way to search for files that use POSIX ACLs in a filesystem -- that is, ACLs other than the so-called minimal ACLs, the familiar rwx for user-group-other -- except painstakingly parsing the output of getfacl ran through find?
--skip-base Skip files that only have the base ACL entries (owner, group, others).
--recursive List the ACLs of all files and directories recursively.
getfacl has a -R or --recursive option, give it a * argument and it will recursively go through all subdirectories and files in that directory. From there it is simple to pipe it into grep and find the attributes you are looking for.