NCDU(1)ncdu manual NCDU(1)NAMEncdu - NCurses Disk Usage
SYNOPSISncdu [options] dir
DESCRIPTIONncdu (NCurses Disk Usage) is a curses-based version of the well-known
'du', and provides a fast way to see what directories are using your
disk space.
OPTIONS
Mode Selection
-h Print a short help message and quit.
-v Print ncdu version and quit.
-f FILE
Load the given file, which has earlier been created with the "-o"
option. If FILE is equivalent to "-", the file is read from
standard input.
For the sake of preventing a screw-up, the current version of ncdu
will assume that the directory information in the imported file
does not represent the filesystem on which the file is being
imported. That is, the refresh and file deletion options in the
browser will be disabled.
dir Scan the given directory.
-o FILE
Export all necessary information to FILE instead of opening the
browser interface. If FILE is "-", the data is written to standard
output. See the examples section below for some handy use cases.
Be warned that the exported data may grow quite large when
exporting a directory with many files. 10.000 files will get you an
export in the order of 600 to 700 KiB uncompressed, or a little
over 100 KiB when compressed with gzip. This scales linearly, so be
prepared to handle a few tens of megabytes when dealing with
millions of files.
Interface options
-0 Don't give any feedback while scanning a directory or importing a
file, other than when a fatal error occurs. Ncurses will not be
initialized until the scan is complete. When exporting the data
with "-o", ncurses will not be initialized at all. This option is
the default when exporting to standard output.
-1 Similar to "-0", but does give feedback on the scanning progress
with a single line of output. This option is the default when
exporting to a file.
In some cases, the ncurses browser interface which you'll see after
the scan/import is complete may look garbled when using this
option. If you're not exporting to a file, "-2" is probably a
better choice.
-2 Provide a full-screen ncurses interface while scanning a directory
or importing a file. This is the only interface that provides
feedback on any non-fatal errors while scanning.
-q Quiet mode. While scanning or importing the directory, ncdu will
update the screen 10 times a second by default, this will be
decreased to once every 2 seconds in quiet mode. Use this feature
to save bandwidth over remote connections. This option has no
effect when "-0" is used.
-r Read-only mode. This will disable the built-in file deletion
feature. This option has no effect when "-o" is used, because there
will not be a browser interface in that case. It has no effect when
"-f" is used, either, because the deletion feature is disabled in
that case anyway.
--si
List sizes using base 10 prefixes, that is, powers of 1000 (KB, MB,
etc), as defined in the International System of Units (SI), instead
of the usual base 2 prefixes, that is, powers of 1024 (KiB, MiB,
etc).
Scan Options
These options affect the scanning progress, and have no effect when
importing directory information from a file.
-x Do not cross filesystem boundaries, i.e. only count files and
directories on the same filesystem as the directory being scanned.
--exclude PATTERN
Exclude files that match PATTERN. The files will still be displayed
by default, but are not counted towards the disk usage statistics.
This argument can be added multiple times to add more patterns.
-X FILE, --exclude-from FILE
Exclude files that match any pattern in FILE. Patterns should be
separated by a newline.
--exclude-caches
Exclude directories containing CACHEDIR.TAG. The directories will
still be displayed, but not their content, and they are not counted
towards the disk usage statistics. See
http://www.brynosaurus.com/cachedir/
KEYS
? Show help + keys + about screen
up, down j, k
Cycle through the items
right, enter, l
Open selected directory
left, <, h
Go to parent directory
n Order by filename (press again for descending order)
s Order by filesize (press again for descending order)
C Order by number of items (press again for descending order)
a Toggle between showing disk usage and showing apparent size.
d Delete the selected file or directory. An error message will be
shown when the contents of the directory do not match or do not
exist anymore on the filesystem.
t Toggle dirs before files when sorting.
g Toggle between showing percentage, graph, both, or none. Percentage
is relative to the size of the current directory, graph is relative
to the largest item in the current directory.
c Toggle display of child item counts.
e Show/hide 'hidden' or 'excluded' files and directories. Please note
that even though you can't see the hidden files and directories,
they are still there and they are still included in the directory
sizes. If you suspect that the totals shown at the bottom of the
screen are not correct, make sure you haven't enabled this option.
i Show information about the current selected item.
r Refresh/recalculate the current directory.
b Spawn shell in current directory.
We first check the $SHELL environment variable of the user for the
preferred shell interpreter. If it's not set, we fall back to the
compile time configured default shell (usually /bin/bash).
q Quit
EXAMPLES
To scan and browse the directory you're currently in, all you need is a
simple:
ncdu
If you want to scan a full filesystem, your root filesystem, for
example, then you'll want to use "-x":
ncdu-x /
Since scanning a large directory may take a while, you can scan a
directory and export the results for later viewing:
ncdu-1xo- / | gzip >export.gz
# ...some time later:
zcat export.gz | ncdu-f-
To export from a cron job, make sure to replace "-1" with "-0" to
suppress any unnecessary output.
You can also export a directory and browse it once scanning is done:
ncdu-o- | tee export.file | ./ncdu -f-
The same is possible with gzip compression, but is a bit kludgey:
ncdu-o- | gzip | tee export.gz | gunzip | ./ncdu -f-
To scan a system remotely, but browse through the files locally:
ssh -C user@system ncdu-o- / | ./ncdu -f-
The "-C" option to ssh enables compression, which will be very useful
over slow links. Remote scanning and local viewing has two major
advantages when compared to running ncdu directly on the remote system:
You can browse through the scanned directory on the local system
without any network latency, and ncdu does not keep the entire
directory structure in memory when exporting, so you won't consume much
memory on the remote system.
HARD LINKS
Every disk usage analysis utility has its own way of (not) counting
hard links. There does not seem to be any universally agreed method of
handling hard links, and it is even inconsistent among different
versions of ncdu. This section explains what each version of ncdu does.
ncdu 1.5 and below does not support any hard link detection at all:
each link is considered a separate inode and its size is counted for
every link. This means that the displayed directory sizes are incorrect
when analyzing directories which contain hard links.
ncdu 1.6 has basic hard link detection: When a link to a previously
encountered inode is detected, the link is considered to have a file
size of zero bytes. Its size is not counted again, and the link is
indicated in the browser interface with a 'H' mark. The displayed
directory sizes are only correct when all links to an inode reside
within that directory. When this is not the case, the sizes may or may
not be correct, depending on which links were considered as "duplicate"
and which as "original". The indicated size of the topmost directory
(that is, the one specified on the command line upon starting ncdu) is
always correct.
ncdu 1.7 and later has improved hard link detection. Each file that has
more than two links has the "H" mark visible in the browser interface.
Each hard link is counted exactly once for every directory it appears
in. The indicated size of each directory is therefore, correctly, the
sum of the sizes of all unique inodes that can be found in that
directory. Note, however, that this may not always be same as the space
that will be reclaimed after deleting the directory, as some inodes may
still be accessible from hard links outside it.
BUGS
Directory hard links are not supported. They will not be detected as
being hard links, and will thus be scanned and counted multiple times.
Some minor glitches may appear when displaying filenames that contain
multibyte or multicolumn characters.
All sizes are internally represented as a signed 64bit integer. If you
have a directory larger than 8 EiB minus one byte, ncdu will clip its
size to 8 EiB minus one byte.
Please report any other bugs you may find at the bug tracker, which can
be found on the web site at http://dev.yorhel.nl/ncdu
AUTHOR
Written by Yoran Heling <projects@yorhel.nl>.
SEE ALSOdu(1)ncdu-1.10g 2014-12-14 NCDU(1)
