du (Unix)

example screenshot of du in a terminal

du (abbreviated from disk usage) is a standard Unix program used to estimate file space usage—space used under a particular directory or files on a file system.

History

The du utility first appeared in version 1 of AT&T UNIX.

Specification

By default, the Single Unix Specification (SUS) specifies that du is to display the file space allocated to each file and directory contained in the current directory. Links will be displayed as the size of the link file, not what is being linked to; the size of the content of directories is displayed, as expected.

As du reports allocation space and not absolute file space, 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. Also the minfree setting that allocates datablocks for the filesystem and the super user processes creates a discrepancy between total bloks and the sum of used and available blocks. The minfree setting is usually set to about 5% of the total filesystem size. For more info see core utils faq.

Usage

du takes a single argument, specifying a pathname for du to work; if it is not specified, the current directory is used. The SUS mandates for du the following options:

-a, display an entry for each file (and not directory) contained in the current directory

-H, calculate disk usage for link references specified on the command line

-k, show sizes as multiples of 1024 bytes, not 512-byte

-L, calculate disk usage for link references anywhere

-s, report only the sum of the usage in the current directory, not for each file

-x, only traverse files and directories on the device on which the pathname argument is specified.

Other Unix and Unix-like operating systems may add extra options. For example, BSD and GNU du specify a -h option, displaying disk usage in a format easier to read by the user, adding units with the appropriate SI prefix (e.g. 10 MB).

Examples

Sum of directories in kilobytes:

 $ du -sk *
 152304  directoryOne
 1856548 directoryTwo

Sum of directories in human-readable format (Byte, Kilobyte, Megabyte, Gigabyte, Terabyte and Petabyte):

 $ du -sh *
 149M directoryOne
 1.8G directoryTwo

disk usage of all subdirectories and files including hidden files within the current directory (sorted by filesize) :

 $ du -sk .[!.]* *| sort -n

disk usage of all subdirectories and files including hidden files within the current directory (sorted by reverse filesize) :

 $ du -sk .[!.]* *| sort -nr

The weight of directories:

 $ du -d 1 -c -h

See also

• List of Unix programs
• Filelight
• Baobab

External links

• du: estimate file space usage – Commands & Utilities Reference, The Single UNIX® Specification, Issue 7 from The Open Group

Manual pages

• du — manual page from GNU coreutils
• du — manual page from OpenBSD
• du — manual page from Dragonflybsd

Other

• Disk space-related utilities at Freshmeat.net