.\"	$OpenBSD: du.1,v 1.21 2007/05/31 19:20:09 jmc Exp $
.\"	$NetBSD: du.1,v 1.6 1996/10/18 07:20:31 thorpej Exp $
.\"
.\" Copyright (c) 1990, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
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.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
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.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
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.\"	@(#)du.1	8.2 (Berkeley) 4/1/94
.\"
.Dd $Mdocdate: May 31 2007 $
.Dt DU 1
.Os
.Sh NAME
.Nm du
.Nd display disk usage statistics
.Sh SYNOPSIS
.Nm du
.Op Fl a | s
.Op Fl chkrx
.Op Fl H | L | P
.Op Ar file ...
.Sh DESCRIPTION
The
.Nm
utility displays the file system block usage for each
.Ar file
argument
and for each directory in the file hierarchy rooted in each directory
argument.
Note that the system block usage is usually greater than
the actual size of the file.
If no file is specified, the block usage of the hierarchy rooted in
the current directory is displayed.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl a
Display an entry for each file in the file hierarchy.
.It Fl c
Display the grand total after all the arguments have been processed.
.It Fl H
Symbolic links on the command line are followed.
(Symbolic links encountered in the tree traversal are not followed.)
.It Fl h
Display numbers in a human readable form.
Use unit suffixes: Byte, Kilobyte, Megabyte, Gigabyte, Terabyte in order to
reduce the number of digits to four or less.
This overrides the
.Fl k
option.
.It Fl k
By default,
.Nm
displays the number of blocks as returned by the
.Xr stat 2
system call, i.e., 512-byte blocks.
If the
.Fl k
flag is specified, the number displayed is the number of 1024-byte
blocks.
Partial numbers of blocks are rounded up.
.It Fl L
All symbolic links are followed.
.It Fl P
No symbolic links are followed.
.It Fl 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
.St -xpg4 .
.It Fl s
Display only the grand total for the specified files.
.It Fl x
File system mount points are not traversed.
.El
.Pp
.Nm
counts the storage used by symbolic links and not the files they
reference unless the
.Fl H
or
.Fl L
option is specified.
If either the
.Fl H
or
.Fl L
options are specified, storage used by any symbolic links which are
followed is not counted or displayed.
The
.Fl H ,
.Fl L ,
and
.Fl P
options override each other and the command's actions are determined
by the last one specified.
.Pp
Files having multiple hard links are counted (and displayed) a single
time per
.Nm
execution.
.Sh ENVIRONMENT
.Bl -tag -width BLOCKSIZE
.It Ev BLOCKSIZE
Block counts will be displayed in units of this size block, unless the
.Fl k
or
.Fl h
option is specified.
.El
.Sh SEE ALSO
.Xr df 1 ,
.Xr fts 3 ,
.Xr symlink 7 ,
.Xr quot 8
.Sh STANDARDS
The
.Nm
utility is compliant with the
.St -p1003.1-2004
specification.
.Pp
The flags
.Op Fl chrP
are extensions to that specification.
.Sh HISTORY
A
.Nm
command appeared in
.At v3 .