Disk Usage
It reports the amount of disk space used by the specified files and for each subdirectory.
du [options]… [file]…
With no arguments, “du”” reports the disk space for the current directory. Normally the disk space is printed in units of 1024 bytes, but this can be overridden
Show counts for all files, not just directories.
Print sizes in bytes, overriding the default block size (*note Block size::).
Print a grand total of all arguments after all arguments have been processed. This can be used to find out the total disk usage of a
given set of files or directories.
Dereference symbolic links that are command line arguments. Does not affect other symbolic links. This is helpful for finding out
the disk usage of directories, such as “/usr/tmp””, which are often symbolic links.
Append a size letter such as “M”” for megabytes to each size. Powers of 1024 are used, not 1000; “M”” stands for 1,048,576 bytes.
Use the “-H”” or “–si”” option if you prefer powers of 1000.
Append a size letter such as “M”” for megabytes to each size. (SI is the International System of Units, which defines these letters
as prefixes.) Powers of 1000 are used, not 1024; “M”” stands for 1,000,000 bytes. Use the “-h”” or “–human-readable”” option if you prefer powers of 1024.
Print sizes in 1024-byte blocks, overriding the default block size (*note Block size::).
Count the size of all files, even if they have appeared already (as a hard link).
Dereference symbolic links (show the disk space used by the file or directory that the link points to instead of the space used by
the link).
Show the total for each directory (and file if -all) that is at most MAX_DEPTH levels down from the root of the hierarchy. The root is at level 0, so “du –max-depth=0″” is equivalent to “du -s””.
Print sizes in megabyte (that is, 1,048,576-byte) blocks.
Display only a total for each argument.
Report the size of each directory separately, not including the sizes of subdirectories.
Skip directories that are on different filesystems from the one that the argument being processed is on.
When recursing, skip subdirectories or files matching PAT. For  example, “du –exclude=””*.o” excludes files whose names end in
“-X FILE””
Like “–exclude””, except take the patterns to exclude from FILE, one per line. If FILE is “-“”, take the patterns from standard
On BSD systems, “du”” reports sizes that are half the correct values for files that are NFS-mounted from HP-UX systems. On HP-UX systems, it reports sizes that are twice the correct values for files that are NFS-mounted from BSD systems. This is due to a flaw in HP-UX; it also affects the HP-UX “du”” program.