1NCDU(1) ncdu manual NCDU(1)
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6 ncdu - NCurses Disk Usage
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9 ncdu [options] dir
10
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. Currently only two schemes are recognized:
116 off to disable colors (the default) and dark for a color scheme
117 intended for dark backgrounds.
118 Scan Options
120 These options affect the scanning progress, and have no effect when
121 importing directory information from a file.
122 -x Do not cross filesystem boundaries, i.e. only count files and
124 directories on the same filesystem as the directory being scanned.
125 --exclude PATTERN
127 Exclude files that match PATTERN. The files will still be displayed
128 by default, but are not counted towards the disk usage statistics.
129 This argument can be added multiple times to add more patterns.
130 -X FILE, --exclude-from FILE
132 Exclude files that match any pattern in FILE. Patterns should be
133 separated by a newline.
134 --exclude-caches
136 Exclude directories containing CACHEDIR.TAG. The directories will
137 still be displayed, but not their content, and they are not counted
138 towards the disk usage statistics. See
139 http://www.brynosaurus.com/cachedir/
140 -L, --follow-symlinks
142 Follow symlinks and count the size of the file they point to. As of
143 ncdu 1.14, this option will not follow symlinks to directories and
144 will count each symlinked file as a unique file (i.e. unlike how
145 hard links are handled). This is subject to change in later
146 versions.
147 --exclude-firmlinks
149 (MacOS only) Exclude firmlinks.
150 --exclude-kernfs
152 (Linux only) Exclude Linux pseudo filesystems, e.g. /proc (procfs),
153 /sys (sysfs).
154 The complete list of currently known pseudo filesystems is: binfmt,
156 bpf, cgroup, cgroup2, debug, devpts, proc, pstore, security,
157 selinux, sys, trace.
158
160 ? Show help + keys + about screen
161 up, down j, k
163 Cycle through the items
164 right, enter, l
166 Open selected directory
167 left, <, h
169 Go to parent directory
170 n Order by filename (press again for descending order)
172 s Order by filesize (press again for descending order)
174 C Order by number of items (press again for descending order)
176 a Toggle between showing disk usage and showing apparent size.
178 M Order by latest child mtime, or modified time. (press again for
180 descending order) Requires the -e flag.
181 d Delete the selected file or directory. An error message will be
183 shown when the contents of the directory do not match or do not
184 exist anymore on the filesystem.
185 t Toggle dirs before files when sorting.
187 g Toggle between showing percentage, graph, both, or none. Percentage
189 is relative to the size of the current directory, graph is relative
190 to the largest item in the current directory.
191 c Toggle display of child item counts.
193 m Toggle display of latest child mtime, or modified time. Requires
195 the -e flag.
196 e Show/hide 'hidden' or 'excluded' files and directories. Please note
198 that even though you can't see the hidden files and directories,
199 they are still there and they are still included in the directory
200 sizes. If you suspect that the totals shown at the bottom of the
201 screen are not correct, make sure you haven't enabled this option.
202 i Show information about the current selected item.
204 r Refresh/recalculate the current directory.
206 b Spawn shell in current directory.
208 Ncdu will determine your preferred shell from the "NCDU_SHELL" or
210 "SHELL" variable (in that order), or will call "/bin/sh" if neither
211 are set. This allows you to also configure another command to be
212 run when he 'b' key is pressed. For example, to spawn the vifm(1)
213 file manager instead of a shell, run ncdu as follows:
214 export NCDU_SHELL=vifm
216 ncdu
217 Ncdu will set the "NCDU_LEVEL" environment variable or increment it
219 before spawning the shell. This variable allows you to detect when
220 your shell is running from within ncdu, which can be useful to
221 avoid nesting multiple instances of ncdu. Ncdu itself does not
222 (currently) warn when attempting to run nested instances.
223 q Quit
225
227 Entries in the browser interface may be prefixed by a one-character
228 flag. These flags have the following meaning:
229 ! An error occurred while reading this directory.
231 . An error occurred while reading a subdirectory, so the indicated
233 size may not be correct.
234 < File or directory is excluded from the statistics by using exclude
236 patterns.
237 > Directory is on another filesystem.
239 ^ Directory is excluded from the statistics due to being a Linux
241 pseudo filesystem.
242 @ This is neither a file nor a folder (symlink, socket, ...).
244 H Same file was already counted (hard link).
246 e Empty directory.
248
250 To scan and browse the directory you're currently in, all you need is a
251 simple:
252 ncdu
254 If you want to scan a full filesystem, your root filesystem, for
256 example, then you'll want to use "-x":
257 ncdu -x /
259 Since scanning a large directory may take a while, you can scan a
261 directory and export the results for later viewing:
262 ncdu -1xo- / | gzip >export.gz
264 # ...some time later:
265 zcat export.gz | ncdu -f-
266 To export from a cron job, make sure to replace "-1" with "-0" to
268 suppress any unnecessary output.
269 You can also export a directory and browse it once scanning is done:
271 ncdu -o- | tee export.file | ./ncdu -f-
273 The same is possible with gzip compression, but is a bit kludgey:
275 ncdu -o- | gzip | tee export.gz | gunzip | ./ncdu -f-
277 To scan a system remotely, but browse through the files locally:
279 ssh -C user@system ncdu -o- / | ./ncdu -f-
281 The "-C" option to ssh enables compression, which will be very useful
283 over slow links. Remote scanning and local viewing has two major
284 advantages when compared to running ncdu directly on the remote system:
285 You can browse through the scanned directory on the local system
286 without any network latency, and ncdu does not keep the entire
287 directory structure in memory when exporting, so you won't consume much
288 memory on the remote system.
289
291 Every disk usage analysis utility has its own way of (not) counting
292 hard links. There does not seem to be any universally agreed method of
293 handling hard links, and it is even inconsistent among different
294 versions of ncdu. This section explains what each version of ncdu does.
295 ncdu 1.5 and below does not support any hard link detection at all:
297 each link is considered a separate inode and its size is counted for
298 every link. This means that the displayed directory sizes are incorrect
299 when analyzing directories which contain hard links.
300 ncdu 1.6 has basic hard link detection: When a link to a previously
302 encountered inode is detected, the link is considered to have a file
303 size of zero bytes. Its size is not counted again, and the link is
304 indicated in the browser interface with a 'H' mark. The displayed
305 directory sizes are only correct when all links to an inode reside
306 within that directory. When this is not the case, the sizes may or may
307 not be correct, depending on which links were considered as "duplicate"
308 and which as "original". The indicated size of the topmost directory
309 (that is, the one specified on the command line upon starting ncdu) is
310 always correct.
311 ncdu 1.7 and later has improved hard link detection. Each file that has
313 more than two links has the "H" mark visible in the browser interface.
314 Each hard link is counted exactly once for every directory it appears
315 in. The indicated size of each directory is therefore, correctly, the
316 sum of the sizes of all unique inodes that can be found in that
317 directory. Note, however, that this may not always be same as the space
318 that will be reclaimed after deleting the directory, as some inodes may
319 still be accessible from hard links outside it.
320
322 Directory hard links are not supported. They will not be detected as
323 being hard links, and will thus be scanned and counted multiple times.
324 Some minor glitches may appear when displaying filenames that contain
326 multibyte or multicolumn characters.
327 All sizes are internally represented as a signed 64bit integer. If you
329 have a directory larger than 8 EiB minus one byte, ncdu will clip its
330 size to 8 EiB minus one byte. When deleting items in a directory with a
331 clipped size, the resulting sizes will be incorrect.
332 Item counts are stored in a signed 32-bit integer without overflow
334 detection. If you have a directory with more than 2 billion files,
335 quite literally anything can happen.
336 On macOS 10.15 and later, running ncdu on the root directory without
338 `--exclude-firmlinks` may cause directories to be scanned and counted
339 multiple times. Firmlink cycles are currently (1.16) not detected, so
340 it may also cause ncdu to get stuck in an infinite loop and eventually
341 run out of memory.
342 Please report any other bugs you may find at the bug tracker, which can
344 be found on the web site at https://dev.yorhel.nl/ncdu
345
347 Written by Yoran Heling <projects@yorhel.nl>.
348
350 du(1)
351ncdu-1.16 2021-07-02 NCDU(1)