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
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15 df [-k][-P|-t][file...]
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18 The df utility shall write the amount of available space and file
19 slots 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 the number of free
26 file slots, or inodes, available; when -t is specified, the output
27 shall contain the total allocated space as well.
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30 The df utility shall conform to the Base Definitions volume of
31 IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
32 The following options shall be supported:
34 -k Use 1024-byte units, instead of the default 512-byte units, when
36 writing space figures.
37 -P Produce output in the format described in the STDOUT section.
39 -t Include total allocated-space figures in the output.
41
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 direc‐
48 tory, or a special file representing the device containing the
49 file system (for example, /dev/dsk/0s1) is specified, the
50 results are unspecified. Otherwise, df shall write the amount
51 of free space in the file system containing the specified file
52 operand.
53
56 Not used.
57
59 None.
60
62 The following environment variables shall affect the execution of df:
63 LANG Provide a default value for the internationalization variables
65 that are unset or null. (See the Base Definitions volume of
66 IEEE Std 1003.1-2001, Section 8.2, Internationalization Vari‐
67 ables for the precedence of internationalization variables used
68 to determine the values of locale categories.)
69 LC_ALL If set to a non-empty string value, override the values of all
71 the other internationalization variables.
72 LC_CTYPE
74 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
84 Determine the location of message catalogs for the processing of
85 LC_MESSAGES .
86
89 Default.
90
92 When both the -k and -P options are specified, the following header
93 line shall be written (in the POSIX locale):
94 "Filesystem 1024-blocks Used Available Capacity Mounted on\n"
97 When the -P option is specified without the -k option, the following
99 header line shall be written (in the POSIX locale):
100 "Filesystem 512-blocks Used Available Capacity Mounted on\n"
103 The implementation may adjust the spacing of the header line and the
105 individual data lines so that the information is presented in orderly
106 columns.
107 The remaining output with -P shall consist of one line of information
109 for each specified file system. These lines shall be formatted as fol‐
110 lows:
111 "%s %d %d %d %d%% %s\n", <file system name>, <total space>,
114 <space used>, <space free>, <percentage used>,
115 <file system root>
116 In the following list, all quantities expressed in 512-byte units
118 (1024-byte when -k is specified) shall be rounded up to the next higher
119 unit. The fields are:
120 <file system name>
122 The name of the file system, in an implementation-defined for‐
124 mat.
125 <total space>
127 The total size of the file system in 512-byte units. The exact
128 meaning of this figure is implementation-defined, but should
129 include <space used>, <space free>, plus any space reserved by
130 the system not normally available to a user.
131 <space used>
133 The total amount of space allocated to existing files in the
134 file system, in 512-byte units.
135 <space free>
137 The total amount of space available within the file system for
138 the creation of new files by unprivileged users, in 512-byte
139 units. When this figure is less than or equal to zero, it shall
140 not be possible to create any new files on the file system with‐
141 out first deleting others, unless the process has appropriate
142 privileges. The figure written may be less than zero.
143 <percentage used>
145 The percentage of the normally available space that is currently
147 allocated to all files on the file system. This shall be calcu‐
148 lated using the fraction:
149 <space used>/( <space used>+ <space free>)
152 expressed as a percentage. This percentage may be greater than 100 if
154 <space free> is less than zero. The percentage value shall be expressed
155 as a positive integer, with any fractional result causing it to be
156 rounded to the next highest integer.
157 <file system root>
159 The directory below which the file system hierarchy appears.
161 The output format is unspecified when -t is used.
164
166 The standard error shall be used only for diagnostic messages.
167
169 None.
170
172 None.
173
175 The following exit values shall be returned:
176 0 Successful completion.
178 >0 An error occurred.
180
183 Default.
184 The following sections are informative.
186
188 On most systems, the "name of the file system, in an implementation-
189 defined format" is the special file on which the file system is
190 mounted.
191 On large file systems, the calculation specified for percentage used
193 can create huge rounding errors.
194
196 1. The following example writes portable information about the /usr
197 file system:
198 df -P /usr
201 2. Assuming that /usr/src is part of the /usr file system, the follow‐
203 ing produces the same output as the previous example:
204 df -P /usr/src
207
209 The behavior of df with the -P option is the default action of the 4.2
210 BSD df utility. The uppercase -P was selected to avoid collision with a
211 known industry extension using -p.
212 Historical df implementations vary considerably in their default out‐
214 put. It was therefore necessary to describe the default output in a
215 loose manner to accommodate all known historical implementations and to
216 add a portable option ( -P) to provide information in a portable for‐
217 mat.
218 The use of 512-byte units is historical practice and maintains compati‐
220 bility with ls and other utilities in this volume of
221 IEEE Std 1003.1-2001. This does not mandate that the file system itself
222 be based on 512-byte blocks. The -k option was added as a compromise
223 measure. It was agreed by the standard developers that 512 bytes was
224 the best default unit because of its complete historical consistency on
225 System V (versus the mixed 512/1024-byte usage on BSD systems), and
226 that a -k option to switch to 1024-byte units was a good compromise.
227 Users who prefer the more logical 1024-byte quantity can easily alias
228 df to df -k without breaking many historical scripts relying on the
229 512-byte units.
230 It was suggested that df and the various related utilities be modified
232 to access a BLOCKSIZE environment variable to achieve consistency and
233 user acceptance. Since this is not historical practice on any system,
234 it is left as a possible area for system extensions and will be re-
235 evaluated in a future version if it is widely implemented.
236
238 None.
239
241 find
242
244 Portions of this text are reprinted and reproduced in electronic form
245 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
246 -- Portable Operating System Interface (POSIX), The Open Group Base
247 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
248 Electrical and Electronics Engineers, Inc and The Open Group. In the
249 event of any discrepancy between this version and the original IEEE and
250 The Open Group Standard, the original IEEE and The Open Group Standard
251 is the referee document. The original Standard can be obtained online
252 at http://www.opengroup.org/unix/online.html .
253IEEE/The Open Group 2003 DF(1P)