This command will find all the files in the /usr directory that have the user ID (UID) of 0, which is the root user, and have the permission of 4000, which is the SUID bit. The SUID bit allows the file to be executed with the privileges of the file owner, regardless of who runs it. The -uid option tests for a specific UID, and the
-perm option tests for a specific permission. The + sign before the permission means that at least those bits are set; the - sign means that exactly those bits are set. The other options are either invalid or do not match the criteria. References:
* LPIC-1 Exam 102 Objectives, Topic 104: Devices, Linux Filesystems, Filesystem Hierarchy Standard,
104.4 Find system files and place files in the correct location, Key Knowledge Areas: Search for files by type, size, or time
* find manual page, -uid and -perm options description
* Find Command in Linux with Practical Examples, Example 8: Find Files with SUID and SGID Permissions