Write a program that logs all file creations, deletions, and renames under the directory named in its command-line argument. The program should monitor events in all of the subdirectories under the specified directory. To obtain a list of all of these subdirectories, you will need to make use of nftw() (Section 18.9). When a new subdirectory is added under the tree or a directory is deleted, the set of monitored subdirectories should be updated accordingly.