1DF(1P) POSIX Programmer's Manual DF(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
12 df — report free disk space
13
15 df [-k] [-P|-t] [file...]
16
18 The df utility shall write the amount of available space and file slots
19 for file systems on which the invoking user has appropriate read
20 access. File systems shall be specified by the file operands; when none
21 are specified, information shall be written for all file systems. The
22 format of the default output from df is unspecified, but all space fig‐
23 ures are reported in 512-byte units, unless the -k option is specified.
24 This output shall contain at least the file system names, amount of
25 available space on each of these file systems, and, if no options other
26 than -t are specified, the number of free file slots, or inodes, avail‐
27 able; when -t is specified, the output shall contain the total allo‐
28 cated space as well.
29
31 The df utility shall conform to the Base Definitions volume of
32 POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
33 The following options shall be supported:
35 -k Use 1024-byte units, instead of the default 512-byte units,
37 when writing space figures.
38 -P Produce output in the format described in the STDOUT section.
40 -t Include total allocated-space figures in the output.
42
44 The following operand shall be supported:
45 file A pathname of a file within the hierarchy of the desired file
47 system. If a file other than a FIFO, a regular file, a
48 directory, or a special file representing the device contain‐
49 ing the file system (for example, /dev/dsk/0s1) is specified,
50 the results are unspecified. If the file operand names a file
51 other than a special file containing a file system, df shall
52 write the amount of free space in the file system containing
53 the specified file operand. Otherwise, df shall write the
54 amount of free space in that file system.
55
57 Not used.
58
60 None.
61
63 The following environment variables shall affect the execution of df:
64 LANG Provide a default value for the internationalization vari‐
66 ables that are unset or null. (See the Base Definitions vol‐
67 ume of POSIX.1‐2017, Section 8.2, Internationalization Vari‐
68 ables for the precedence of internationalization variables
69 used to determine the values of locale categories.)
70 LC_ALL If set to a non-empty string value, override the values of
72 all the other internationalization variables.
73 LC_CTYPE Determine the locale for the interpretation of sequences of
75 bytes of text data as characters (for example, single-byte as
76 opposed to multi-byte characters in arguments).
77 LC_MESSAGES
79 Determine the locale that should be used to affect the format
80 and contents of diagnostic messages written to standard error
81 and informative messages written to standard output.
82 NLSPATH Determine the location of message catalogs for the processing
84 of LC_MESSAGES.
85
87 Default.
88
90 When both the -k and -P options are specified, the following header
91 line shall be written (in the POSIX locale):
92 "Filesystem 1024-blocks Used Available Capacity Mounted on\n"
95 When the -P option is specified without the -k option, the following
97 header line shall be written (in the POSIX locale):
98 "Filesystem 512-blocks Used Available Capacity Mounted on\n"
101 The implementation may adjust the spacing of the header line and the
103 individual data lines so that the information is presented in orderly
104 columns.
105 The remaining output with -P shall consist of one line of information
107 for each specified file system. These lines shall be formatted as fol‐
108 lows:
109 "%s %d %d %d %d%% %s\n", <file system name>, <total space>,
112 <space used>, <space free>, <percentage used>,
113 <file system root>
114 In the following list, all quantities expressed in 512-byte units
116 (1024-byte when -k is specified) shall be rounded up to the next higher
117 unit. The fields are:
118 <file system name>
120 The name of the file system, in an implementation-defined
121 format.
122 <total space>
124 The total size of the file system in 512-byte units. The
125 exact meaning of this figure is implementation-defined, but
126 should include <space used>, <space free>, plus any space
127 reserved by the system not normally available to a user.
128 <space used>
130 The total amount of space allocated to existing files in the
131 file system, in 512-byte units.
132 <space free>
134 The total amount of space available within the file system
135 for the creation of new files by unprivileged users, in
136 512-byte units. When this figure is less than or equal to
137 zero, it shall not be possible to create any new files on the
138 file system without first deleting others, unless the process
139 has appropriate privileges. The figure written may be less
140 than zero.
141 <percentage used>
143 The percentage of the normally available space that is cur‐
144 rently allocated to all files on the file system. This shall
145 be calculated using the fraction:
146 <space used>/( <space used>+ <space free>)
149 expressed as a percentage. This percentage may be greater
151 than 100 if <space free> is less than zero. The percentage
152 value shall be expressed as a positive integer, with any
153 fractional result causing it to be rounded to the next high‐
154 est integer.
155 <file system root>
157 The directory below which the file system hierarchy appears.
158 The output format is unspecified when -t is used.
160
162 The standard error shall be used only for diagnostic messages.
163
165 None.
166
168 None.
169
171 The following exit values shall be returned:
172 0 Successful completion.
174 >0 An error occurred.
176
178 Default.
179 The following sections are informative.
181
183 On most systems, the ``name of the file system, in an implementation-
184 defined format'' is the special file on which the file system is
185 mounted.
186 On large file systems, the calculation specified for percentage used
188 can create huge rounding errors.
189
191 1. The following example writes portable information about the /usr
192 file system:
193 df -P /usr
196 2. Assuming that /usr/src is part of the /usr file system, the follow‐
198 ing produces the same output as the previous example:
199 df -P /usr/src
202
204 The behavior of df with the -P option is the default action of the 4.2
205 BSD df utility. The uppercase -P was selected to avoid collision with a
206 known industry extension using -p.
207 Historical df implementations vary considerably in their default out‐
209 put. It was therefore necessary to describe the default output in a
210 loose manner to accommodate all known historical implementations and to
211 add a portable option (-P) to provide information in a portable format.
212 The use of 512-byte units is historical practice and maintains compati‐
214 bility with ls and other utilities in this volume of POSIX.1‐2017. This
215 does not mandate that the file system itself be based on 512-byte
216 blocks. The -k option was added as a compromise measure. It was agreed
217 by the standard developers that 512 bytes was the best default unit
218 because of its complete historical consistency on System V (versus the
219 mixed 512/1024-byte usage on BSD systems), and that a -k option to
220 switch to 1024-byte units was a good compromise. Users who prefer the
221 more logical 1024-byte quantity can easily alias df to df -k without
222 breaking many historical scripts relying on the 512-byte units.
223 It was suggested that df and the various related utilities be modified
225 to access a BLOCKSIZE environment variable to achieve consistency and
226 user acceptance. Since this is not historical practice on any system,
227 it is left as a possible area for system extensions and will be re-
228 evaluated in a future version if it is widely implemented.
229
231 None.
232
234 find
235 The Base Definitions volume of POSIX.1‐2017, Chapter 8, Environment
237 Variables, Section 12.2, Utility Syntax Guidelines
238
240 Portions of this text are reprinted and reproduced in electronic form
241 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
242 table Operating System Interface (POSIX), The Open Group Base Specifi‐
243 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
244 Electrical and Electronics Engineers, Inc and The Open Group. In the
245 event of any discrepancy between this version and the original IEEE and
246 The Open Group Standard, the original IEEE and The Open Group Standard
247 is the referee document. The original Standard can be obtained online
248 at http://www.opengroup.org/unix/online.html .
249 Any typographical or formatting errors that appear in this page are
251 most likely to have been introduced during the conversion of the source
252 files to man page format. To report such errors, see https://www.ker‐
253 nel.org/doc/man-pages/reporting_bugs.html .
254IEEE/The Open Group 2017 DF(1P)