whereis：查找程序的源、二进制文件或手册。

Usage:
 whereis [options] file

Options:
 -f <file>  define search scope
 -b         search only binaries
 -B <dirs>  define binaries lookup path
 -m         search only manual paths
 -M <dirs>  define man lookup path
 -s         search only sources path
 -S <dirs>  define sources lookup path
 -u         search from unusual enties
 -V         output version information and exit
 -h         display this help and exit