du is a Unix computer program to display the amount of disk
space used under a particular directory or files on a file system.
du counts the disk space by walking the directory tree.
As such, the amount of space on a file system shown by du may vary from that
shown by df if files have been deleted but their blocks not yet freed.
In Linux, it is a part of the GNU Coreutils package.
The du utility first appeared in version 1 of AT&T
UNIX.
Example
The -k flag will show the sizes in 1K blocks,
rather than the default of 512 byte blocks.
$du -k /seclog
4
/seclog/lost+found
132
/seclog/backup/aix7
136
/seclog/backup
44044
/seclog/temp
439264 /seclog
