指令：du
參數：
-a Display an entry for each file in a file hierarchy.
-c Display a grand total.
-d depth
Display an entry for all files and directories depth directories deep.
-H Symbolic links on the command line are followed, symbolic links in file hierarchies are not followed.
-h "Human-readable" output. Use unit suffixes: Byte, Kilobyte, Megabyte, Gigabyte, Terabyte and Petabyte.
-I mask
Ignore files and directories matching the specified mask.
-g Display block counts in 1073741824-byte (1-Gbyte) blocks.
-k Display block counts in 1024-byte (1-Kbyte) blocks.
-L Symbolic links on the command line and in file hierarchies are followed.
-m Display block counts in 1048576-byte (1-Mbyte) blocks.
-P No symbolic links are followed. This is the default.
-r Generate messages about directories that cannot be read, files that cannot be opened, and so on. This is the default case.
This option exists solely for conformance with X/Open Portability Guide Issue 4 (``XPG4'').
-s Display an entry for each specified file. (Equivalent to -d 0)
-x File system mount points are not traversed.
