1NCDU(1) ncdu manual NCDU(1)
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6 ncdu - NCurses Disk Usage
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9 ncdu [options] dir
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12 ncdu (NCurses Disk Usage) is a curses-based version of the well-known
13 'du', and provides a fast way to see what directories are using your
14 disk space.
15
17 Mode Selection
18 -h, --help
19 Print a short help message and quit.
20 -v, -V, --version
22 Print ncdu version and quit.
23 -f FILE
25 Load the given file, which has earlier been created with the "-o"
26 option. If FILE is equivalent to "-", the file is read from
27 standard input.
28 For the sake of preventing a screw-up, the current version of ncdu
30 will assume that the directory information in the imported file
31 does not represent the filesystem on which the file is being
32 imported. That is, the refresh, file deletion and shell spawning
33 options in the browser will be disabled.
34 dir Scan the given directory.
36 -o FILE
38 Export all necessary information to FILE instead of opening the
39 browser interface. If FILE is "-", the data is written to standard
40 output. See the examples section below for some handy use cases.
41 Be warned that the exported data may grow quite large when
43 exporting a directory with many files. 10.000 files will get you an
44 export in the order of 600 to 700 KiB uncompressed, or a little
45 over 100 KiB when compressed with gzip. This scales linearly, so be
46 prepared to handle a few tens of megabytes when dealing with
47 millions of files.
48 -e Enable extended information mode. This will, in addition to the
50 usual file information, also read the ownership, permissions and
51 last modification time for each file. This will result in higher
52 memory usage (by roughly ~30%) and in a larger output file when
53 exporting.
54 When using the file export/import function, this flag will need to
56 be added both when exporting (to make sure the information is added
57 to the export), and when importing (to read this extra information
58 in memory). This flag has no effect when importing a file that has
59 been exported without the extended information.
60 This enables viewing and sorting by the latest child mtime, or
62 modified time, using 'm' and 'M', respectively.
63 Interface options
65 -0 Don't give any feedback while scanning a directory or importing a
66 file, other than when a fatal error occurs. Ncurses will not be
67 initialized until the scan is complete. When exporting the data
68 with "-o", ncurses will not be initialized at all. This option is
69 the default when exporting to standard output.
70 -1 Similar to "-0", but does give feedback on the scanning progress
72 with a single line of output. This option is the default when
73 exporting to a file.
74 In some cases, the ncurses browser interface which you'll see after
76 the scan/import is complete may look garbled when using this
77 option. If you're not exporting to a file, "-2" is probably a
78 better choice.
79 -2 Provide a full-screen ncurses interface while scanning a directory
81 or importing a file. This is the only interface that provides
82 feedback on any non-fatal errors while scanning.
83 -q Quiet mode. While scanning or importing the directory, ncdu will
85 update the screen 10 times a second by default, this will be
86 decreased to once every 2 seconds in quiet mode. Use this feature
87 to save bandwidth over remote connections. This option has no
88 effect when "-0" is used.
89 -r Read-only mode. This will disable the built-in file deletion
91 feature. This option has no effect when "-o" is used, because there
92 will not be a browser interface in that case. It has no effect when
93 "-f" is used, either, because the deletion feature is disabled in
94 that case anyway.
95 WARNING: This option will only prevent deletion through the file
97 browser. It is still possible to spawn a shell from ncdu and delete
98 or modify files from there. To disable that feature as well, pass
99 the "-r" option twice (see "-rr").
100 -rr In addition to "-r", this will also disable the shell spawning
102 feature of the file browser.
103 --si
105 List sizes using base 10 prefixes, that is, powers of 1000 (KB, MB,
106 etc), as defined in the International System of Units (SI), instead
107 of the usual base 2 prefixes, that is, powers of 1024 (KiB, MiB,
108 etc).
109 --confirm-quit
111 Requires a confirmation before quitting ncdu. Very helpful when you
112 accidentally press 'q' during or after a very long scan.
113 --color SCHEME
115 Select a color scheme. The following schemes are recognized: off to
116 disable colors, dark for a color scheme intended for dark
117 backgrounds and dark-bg for a variation of the dark color scheme
118 that also works in terminals with a light background.
119 The default is dark-bg unless the "NO_COLOR" environment variable
121 is set.
122 Scan Options
124 These options affect the scanning progress, and have no effect when
125 importing directory information from a file.
126 -x Do not cross filesystem boundaries, i.e. only count files and
128 directories on the same filesystem as the directory being scanned.
129 --exclude PATTERN
131 Exclude files that match PATTERN. The files will still be displayed
132 by default, but are not counted towards the disk usage statistics.
133 This argument can be added multiple times to add more patterns.
134 -X FILE, --exclude-from FILE
136 Exclude files that match any pattern in FILE. Patterns should be
137 separated by a newline.
138 --exclude-caches
140 Exclude directories containing CACHEDIR.TAG. The directories will
141 still be displayed, but not their content, and they are not counted
142 towards the disk usage statistics. See
143 http://www.brynosaurus.com/cachedir/
144 -L, --follow-symlinks
146 Follow symlinks and count the size of the file they point to. As of
147 ncdu 1.14, this option will not follow symlinks to directories and
148 will count each symlinked file as a unique file (i.e. unlike how
149 hard links are handled). This is subject to change in later
150 versions.
151 --exclude-firmlinks
153 (MacOS only) Exclude firmlinks.
154 --exclude-kernfs
156 (Linux only) Exclude Linux pseudo filesystems, e.g. /proc (procfs),
157 /sys (sysfs).
158 The complete list of currently known pseudo filesystems is: binfmt,
160 bpf, cgroup, cgroup2, debug, devpts, proc, pstore, security,
161 selinux, sys, trace.
162
164 ? Show help + keys + about screen
165 up, down, j, k
167 Cycle through the items
168 right, enter, l
170 Open selected directory
171 left, <, h
173 Go to parent directory
174 n Order by filename (press again for descending order)
176 s Order by filesize (press again for descending order)
178 C Order by number of items (press again for descending order)
180 a Toggle between showing disk usage and showing apparent size.
182 M Order by latest child mtime, or modified time. (press again for
184 descending order) Requires the -e flag.
185 d Delete the selected file or directory. An error message will be
187 shown when the contents of the directory do not match or do not
188 exist anymore on the filesystem.
189 t Toggle dirs before files when sorting.
191 g Toggle between showing percentage, graph, both, or none. Percentage
193 is relative to the size of the current directory, graph is relative
194 to the largest item in the current directory.
195 c Toggle display of child item counts.
197 m Toggle display of latest child mtime, or modified time. Requires
199 the -e flag.
200 e Show/hide 'hidden' or 'excluded' files and directories. Please note
202 that even though you can't see the hidden files and directories,
203 they are still there and they are still included in the directory
204 sizes. If you suspect that the totals shown at the bottom of the
205 screen are not correct, make sure you haven't enabled this option.
206 i Show information about the current selected item.
208 r Refresh/recalculate the current directory.
210 b Spawn shell in current directory.
212 Ncdu will determine your preferred shell from the "NCDU_SHELL" or
214 "SHELL" variable (in that order), or will call "/bin/sh" if neither
215 are set. This allows you to also configure another command to be
216 run when he 'b' key is pressed. For example, to spawn the vifm(1)
217 file manager instead of a shell, run ncdu as follows:
218 export NCDU_SHELL=vifm
220 ncdu
221 Ncdu will set the "NCDU_LEVEL" environment variable or increment it
223 before spawning the shell. This variable allows you to detect when
224 your shell is running from within ncdu, which can be useful to
225 avoid nesting multiple instances of ncdu. Ncdu itself does not
226 (currently) warn when attempting to run nested instances.
227 q Quit
229
231 Entries in the browser interface may be prefixed by a one-character
232 flag. These flags have the following meaning:
233 ! An error occurred while reading this directory.
235 . An error occurred while reading a subdirectory, so the indicated
237 size may not be correct.
238 < File or directory is excluded from the statistics by using exclude
240 patterns.
241 > Directory is on another filesystem.
243 ^ Directory is excluded from the statistics due to being a Linux
245 pseudo filesystem.
246 @ This is neither a file nor a folder (symlink, socket, ...).
248 H Same file was already counted (hard link).
250 e Empty directory.
252
254 To scan and browse the directory you're currently in, all you need is a
255 simple:
256 ncdu
258 If you want to scan a full filesystem, your root filesystem, for
260 example, then you'll want to use "-x":
261 ncdu -x /
263 Since scanning a large directory may take a while, you can scan a
265 directory and export the results for later viewing:
266 ncdu -1xo- / | gzip >export.gz
268 # ...some time later:
269 zcat export.gz | ncdu -f-
270 To export from a cron job, make sure to replace "-1" with "-0" to
272 suppress any unnecessary output.
273 You can also export a directory and browse it once scanning is done:
275 ncdu -o- | tee export.file | ./ncdu -f-
277 The same is possible with gzip compression, but is a bit kludgey:
279 ncdu -o- | gzip | tee export.gz | gunzip | ./ncdu -f-
281 To scan a system remotely, but browse through the files locally:
283 ssh -C user@system ncdu -o- / | ./ncdu -f-
285 The "-C" option to ssh enables compression, which will be very useful
287 over slow links. Remote scanning and local viewing has two major
288 advantages when compared to running ncdu directly on the remote system:
289 You can browse through the scanned directory on the local system
290 without any network latency, and ncdu does not keep the entire
291 directory structure in memory when exporting, so you won't consume much
292 memory on the remote system.
293
295 Every disk usage analysis utility has its own way of (not) counting
296 hard links. There does not seem to be any universally agreed method of
297 handling hard links, and it is even inconsistent among different
298 versions of ncdu. This section explains what each version of ncdu does.
299 ncdu 1.5 and below does not support any hard link detection at all:
301 each link is considered a separate inode and its size is counted for
302 every link. This means that the displayed directory sizes are incorrect
303 when analyzing directories which contain hard links.
304 ncdu 1.6 has basic hard link detection: When a link to a previously
306 encountered inode is detected, the link is considered to have a file
307 size of zero bytes. Its size is not counted again, and the link is
308 indicated in the browser interface with a 'H' mark. The displayed
309 directory sizes are only correct when all links to an inode reside
310 within that directory. When this is not the case, the sizes may or may
311 not be correct, depending on which links were considered as "duplicate"
312 and which as "original". The indicated size of the topmost directory
313 (that is, the one specified on the command line upon starting ncdu) is
314 always correct.
315 ncdu 1.7 and later has improved hard link detection. Each file that has
317 more than two links has the "H" mark visible in the browser interface.
318 Each hard link is counted exactly once for every directory it appears
319 in. The indicated size of each directory is therefore, correctly, the
320 sum of the sizes of all unique inodes that can be found in that
321 directory. Note, however, that this may not always be same as the space
322 that will be reclaimed after deleting the directory, as some inodes may
323 still be accessible from hard links outside it.
324
326 Directory hard links are not supported. They will not be detected as
327 being hard links, and will thus be scanned and counted multiple times.
328 Some minor glitches may appear when displaying filenames that contain
330 multibyte or multicolumn characters.
331 All sizes are internally represented as a signed 64bit integer. If you
333 have a directory larger than 8 EiB minus one byte, ncdu will clip its
334 size to 8 EiB minus one byte. When deleting items in a directory with a
335 clipped size, the resulting sizes will be incorrect.
336 Item counts are stored in a signed 32-bit integer without overflow
338 detection. If you have a directory with more than 2 billion files,
339 quite literally anything can happen.
340 On macOS 10.15 and later, running ncdu on the root directory without
342 `--exclude-firmlinks` may cause directories to be scanned and counted
343 multiple times. Firmlink cycles are currently (1.16) not detected, so
344 it may also cause ncdu to get stuck in an infinite loop and eventually
345 run out of memory.
346 Please report any other bugs you may find at the bug tracker, which can
348 be found on the web site at https://dev.yorhel.nl/ncdu
349
351 Written by Yoran Heling <projects@yorhel.nl>.
352
354 du(1)
355ncdu-1.16 2021-10-07 NCDU(1)