1DU(1P) POSIX Programmer's Manual DU(1P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
13 du — estimate file space usage
14
16 du [−a|−s] [−kx] [−H|−L] [file...]
17
19 By default, the du utility shall write to standard output the size of
20 the file space allocated to, and the size of the file space allocated
21 to each subdirectory of, the file hierarchy rooted in each of the spec‐
22 ified files. By default, when a symbolic link is encountered on the
23 command line or in the file hierarchy, du shall count the size of the
24 symbolic link (rather than the file referenced by the link), and shall
25 not follow the link to another portion of the file hierarchy. The size
26 of the file space allocated to a file of type directory shall be
27 defined as the sum total of space allocated to all files in the file
28 hierarchy rooted in the directory plus the space allocated to the
29 directory itself.
30 When du cannot stat() files or stat() or read directories, it shall
32 report an error condition and the final exit status is affected. Files
33 with multiple links shall be counted and written for only one entry.
34 The directory entry that is selected in the report is unspecified. By
35 default, file sizes shall be written in 512-byte units, rounded up to
36 the next 512-byte unit.
37
39 The du utility shall conform to the Base Definitions volume of
40 POSIX.1‐2008, Section 12.2, Utility Syntax Guidelines.
41 The following options shall be supported:
43 −a In addition to the default output, report the size of each
45 file not of type directory in the file hierarchy rooted in
46 the specified file. Regardless of the presence of the −a
47 option, non-directories given as file operands shall always
48 be listed.
49 −H If a symbolic link is specified on the command line, du shall
51 count the size of the file or file hierarchy referenced by
52 the link.
53 −k Write the files sizes in units of 1024 bytes, rather than the
55 default 512-byte units.
56 −L If a symbolic link is specified on the command line or
58 encountered during the traversal of a file hierarchy, du
59 shall count the size of the file or file hierarchy referenced
60 by the link.
61 −s Instead of the default output, report only the total sum for
63 each of the specified files.
64 −x When evaluating file sizes, evaluate only those files that
66 have the same device as the file specified by the file oper‐
67 and.
68 Specifying more than one of the mutually-exclusive options −H and −L
70 shall not be considered an error. The last option specified shall
71 determine the behavior of the utility.
72
74 The following operand shall be supported:
75 file The pathname of a file whose size is to be written. If no
77 file is specified, the current directory shall be used.
78
80 Not used.
81
83 None.
84
86 The following environment variables shall affect the execution of du:
87 LANG Provide a default value for the internationalization vari‐
89 ables that are unset or null. (See the Base Definitions vol‐
90 ume of POSIX.1‐2008, Section 8.2, Internationalization Vari‐
91 ables for the precedence of internationalization variables
92 used to determine the values of locale categories.)
93 LC_ALL If set to a non-empty string value, override the values of
95 all the other internationalization variables.
96 LC_CTYPE Determine the locale for the interpretation of sequences of
98 bytes of text data as characters (for example, single-byte as
99 opposed to multi-byte characters in arguments).
100 LC_MESSAGES
102 Determine the locale that should be used to affect the format
103 and contents of diagnostic messages written to standard
104 error.
105 NLSPATH Determine the location of message catalogs for the processing
107 of LC_MESSAGES.
108
110 Default.
111
113 The output from du shall consist of the amount of space allocated to a
114 file and the name of the file, in the following format:
115 "%d %s\n", <size>, <pathname>
117
119 The standard error shall be used only for diagnostic messages.
120
122 None.
123
125 None.
126
128 The following exit values shall be returned:
129 0 Successful completion.
131 >0 An error occurred.
133
135 Default.
136 The following sections are informative.
138
140 None.
141
143 None.
144
146 The use of 512-byte units is historical practice and maintains compati‐
147 bility with ls and other utilities in this volume of POSIX.1‐2008. This
148 does not mandate that the file system itself be based on 512-byte
149 blocks. The −k option was added as a compromise measure. It was agreed
150 by the standard developers that 512 bytes was the best default unit
151 because of its complete historical consistency on System V (versus the
152 mixed 512/1024-byte usage on BSD systems), and that a −k option to
153 switch to 1024-byte units was a good compromise. Users who prefer the
154 1024-byte quantity can easily alias du to du −k without breaking the
155 many historical scripts relying on the 512-byte units.
156 The −b option was added to an early proposal to provide a resolution to
158 the situation where System V and BSD systems give figures for file
159 sizes in blocks, which is an implementation-defined concept. (In common
160 usage, the block size is 512 bytes for System V and 1024 bytes for BSD
161 systems.) However, −b was later deleted, since the default was eventu‐
162 ally decided as 512-byte units.
163 Historical file systems provided no way to obtain exact figures for the
165 space allocation given to files. There are two known areas of inaccura‐
166 cies in historical file systems: cases of indirect blocks being used by
167 the file system or sparse files yielding incorrectly high values. An
168 indirect block is space used by the file system in the storage of the
169 file, but that need not be counted in the space allocated to the file.
170 A sparse file is one in which an lseek() call has been made to a posi‐
171 tion beyond the end of the file and data has subsequently been written
172 at that point. A file system need not allocate all the intervening
173 zero-filled blocks to such a file. It is up to the implementation to
174 define exactly how accurate its methods are.
175 The −a and −s options were mutually-exclusive in the original version
177 of du. The POSIX Shell and Utilities description is implied by the
178 language in the SVID where −s is described as causing ``only the grand
179 total'' to be reported. Some systems may produce output for −sa, but a
180 Strictly Conforming POSIX Shell and Utilities Application cannot use
181 that combination.
182 The −a and −s options were adopted from the SVID except that the System
184 V behavior of not listing non-directories explicitly given as operands,
185 unless the −a option is specified, was considered a bug; the BSD-based
186 behavior (report for all operands) is mandated. The default behavior of
187 du in the SVID with regard to reporting the failure to read files (it
188 produces no messages) was considered counter-intuitive, and thus it was
189 specified that the POSIX Shell and Utilities default behavior shall be
190 to produce such messages. These messages can be turned off with shell
191 redirection to achieve the System V behavior.
192 The −x option is historical practice on recent BSD systems. It has been
194 adopted by this volume of POSIX.1‐2008 because there was no other his‐
195 torical method of limiting the du search to a single file hierarchy.
196 This limitation of the search is necessary to make it possible to
197 obtain file space usage information about a file system on which other
198 file systems are mounted, without having to resort to a lengthy find
199 and awk script.
200
202 None.
203
205 ls
206 The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment
208 Variables, Section 12.2, Utility Syntax Guidelines
209 The System Interfaces volume of POSIX.1‐2008, fstatat()
211
213 Portions of this text are reprinted and reproduced in electronic form
214 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
215 -- Portable Operating System Interface (POSIX), The Open Group Base
216 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
217 cal and Electronics Engineers, Inc and The Open Group. (This is
218 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
219 event of any discrepancy between this version and the original IEEE and
220 The Open Group Standard, the original IEEE and The Open Group Standard
221 is the referee document. The original Standard can be obtained online
222 at http://www.unix.org/online.html .
223 Any typographical or formatting errors that appear in this page are
225 most likely to have been introduced during the conversion of the source
226 files to man page format. To report such errors, see https://www.ker‐
227 nel.org/doc/man-pages/reporting_bugs.html .
228IEEE/The Open Group 2013 DU(1P)