ncdu-zig/ncdu.1

.\" SPDX-FileCopyrightText: Yorhel <projects@yorhel.nl>
.\" SPDX-License-Identifier: MIT
.Dd March 5, 2025
.Dt NCDU 1
.Os
.Sh NAME
.Nm ncdu
.Nd NCurses Disk Usage
.
.Sh SYNOPSIS
.Nm
.Op Fl f Ar file
.Op Fl o Ar file
.Op Fl O Ar file
.Op Fl e , \-extended , \-no\-extended
.Op Fl \-ignore\-config
.Op Fl x , \-one\-file\-system , \-cross\-file\-system
.Op Fl \-exclude Ar pattern
.Op Fl X , \-exclude\-from Ar file
.Op Fl \-include\-caches , \-exclude\-caches
.Op Fl L , \-follow\-symlinks , \-no\-follow\-symlinks
.Op Fl \-include\-kernfs , \-exclude\-kernfs
.Op Fl t , \-threads Ar num
.Op Fl c , \-compress , \-no\-compress
.Op Fl \-compress\-level Ar num
.Op Fl \-export\-block\-size Ar num
.Op Fl 0 , 1 , 2
.Op Fl q , \-slow\-ui\-updates , \-fast\-ui\-updates
.Op Fl \-enable\-shell , \-disable\-shell
.Op Fl \-enable\-delete , \-disable\-delete
.Op Fl \-enable\-refresh , \-disable\-refresh
.Op Fl r
.Op Fl \-si , \-no\-si
.Op Fl \-disk\-usage , \-apparent\-size
.Op Fl \-show\-hidden , \-hide\-hidden
.Op Fl \-show\-itemcount , \-hide\-itemcount
.Op Fl \-show\-mtime , \-hide\-mtime
.Op Fl \-show\-graph , \-hide\-graph
.Op Fl \-show\-percent , \-hide\-percent
.Op Fl \-graph\-style Ar hash | half\-block | eighth\-block
.Op Fl \-shared\-column Ar off | shared | unique
.Op Fl \-sort Ar column
.Op Fl \-enable\-natsort , \-disable\-natsort
.Op Fl \-group\-directories\-first , \-no\-group\-directories\-first
.Op Fl \-confirm\-quit , \-no\-confirm\-quit
.Op Fl \-confirm\-delete , \-no\-confirm\-delete
.Op Fl \-color Ar off | dark | dark-bg
.Op Ar path
.Nm
.Op Fl h , \-help
.Nm
.Op Fl v , V , \-version
.
.Sh DESCRIPTION
.Nm
(NCurses Disk Usage) is an interactive curses-based version of the well-known
.Xr du 1 ,
and provides a fast way to see what directories are using your disk space.
.
.Sh OPTIONS
.Ss Mode Selection
.Bl -tag -width Ds
.It Fl h , \-help
Print a short help message and quit.
.It Fl v , V , \-version
Print version and quit.
.It Fl f Ar file
Load the given file, which has earlier been created with the
.Fl o
or
.Fl O
flag.
If
.Ar file
is equivalent to '\-', the file is read from standard input.
Reading from standard input is only supported for the JSON format.
.Pp
For the sake of preventing a screw-up, the current version of
.Nm
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, file deletion and shell spawning options in the browser
will be disabled.
.It Ar dir
Scan the given directory.
.It Fl o Ar file
Export the directory tree in JSON format to
.Ar file
instead of opening the browser interface.
If
.Ar file
is '\-', the data is written to standard output.
See the examples section below for some handy use cases.
.Pp
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.
.Pp
Consider enabling
.Fl c
to output Zstandard-compressed JSON, which can significantly reduce size of the
exported data.
.Pp
When running a multi-threaded scan or when scanning a directory tree that may
not fit in memory, consider using
.Fl O
instead.
.It Fl O Ar file
Export the directory tree in binary format to
.Ar file
instead of opening the browser interface.
If
.Ar file
is '\-', the data is written to standard output.
The binary format has built-in compression, supports low-memory multi-threaded
export (in combination with
.Fl t )
and can be browsed without importing the entire directory tree into memory.
.It Fl e , \-extended , \-no\-extended
Enable/disable extended information mode.
This will, in addition to the usual file information, also read the ownership,
permissions and last modification time for each file.
This will result in higher memory usage (by roughly ~30%) and in a larger
output file when exporting.
.Pp
When using the file export/import function, this flag should be added both when
exporting (to make sure the information is added to the export) and when
importing (to read this extra information in memory).
This flag has no effect when importing a file that has been exported without
the extended information.
.Pp
This enables viewing and sorting by the latest child mtime, or modified time,
using 'm' and 'M', respectively.
.It Fl \-ignore\-config
Do not attempt to load any configuration files.
.El
.
.Ss Scan Options
These options affect the scanning progress, they have no effect when importing
directory information from a file.
.Bl -tag -width Ds
.It Fl x , \-one\-file\-system
Do not cross filesystem boundaries, i.e. only count files and directories on
the same filesystem as the directory being scanned.
.It Fl \-cross\-file\-system
Do cross filesystem boundaries.
This is the default, but can be specified to overrule a previously configured
.Fl x .
.It Fl \-exclude Ar pattern
Exclude files that match
.Ar pattern .
The files are still displayed by default, but are not counted towards the disk
usage statistics.
This argument can be added multiple times to add more patterns.
.It Fl X , \-exclude\-from Ar file
Exclude files that match any pattern in
.Ar file .
Patterns should be separated by a newline.
.It Fl \-include\-caches , \-exclude\-caches
Include (default) or exclude directories containing
.Pa CACHEDIR.TAG .
Excluded cache directories are still displayed, but their contents will not be
scanned or counted towards the disk usage statistics.
.Lk https://bford.info/cachedir/
.It Fl L , \-follow\-symlinks , \-no\-follow\-symlinks
Follow (or not) symlinks and count the size of the file they point to.
This option does not follow symlinks to directories and will cause each
symlinked file to count as a unique file.
This is different from how hard links are handled.
The exact counting behavior of this flag is subject to change in the future.
.It Fl \-include\-kernfs , \-exclude\-kernfs
(Linux only) Include (default) or exclude Linux pseudo filesystems such as
.Pa /proc
(procfs) and
.Pa /sys
(sysfs).
.Pp
The complete list of currently known pseudo filesystems is: binfmt, bpf, cgroup,
cgroup2, debug, devpts, proc, pstore, security, selinux, sys, trace.
.It Fl t , \-threads Ar num
Number of threads to use when scanning the filesystem, defaults to 1.
.Pp
In single-threaded mode, the JSON export (see
.Fl o )
can operate with very little memory, but in multi-threaded mode the entire
directory tree is first constructed in memory and written out after the
filesystem scan has completed,
This causes a delay in output and requires significantly more memory for large
directory trees.
The binary format (see
.Fl O )
does not have this problem and supports efficient exporting with any number of
threads.
.El
.
.Ss Export Options
These options affect behavior when exporting to file with the
.Fl o
or
.Fl O
options.
.Bl -tag -width Ds
.It Fl c , \-compress , \-no\-compress
Enable or disable Zstandard compression when exporting to JSON (see
.Fl o ) .
.It Fl \-compress\-level Ar num
Set the Zstandard compression level when using
.Fl O
or
.Fl c .
Valid values are 1 (fastest) to 19 (slowest).
Defaults to 4.
.It Fl \-export\-block\-size Ar num
Set the block size, in kibibytes, for the binary export format (see
.Fl O ) .
Larger blocks require more memory but result in better compression efficiency.
This option can be combined with a higher
.Fl \-compress\-level
for even better compression.
.Pp
Accepted values are between 4 and 16000.
The defaults is to start at 64 KiB and then gradually increase the block size
for large exports.
.El
.
.Ss Interface Options
.Bl -tag -width Ds
.It Fl 0
Don't give any feedback while scanning a directory or importing a file, except
when a fatal error occurs.
Ncurses will not be initialized until the scan is complete.
When exporting the data with
.Fl o ,
ncurses will not be initialized at all.
This option is the default when exporting to standard output.
.It Fl 1
Write progress information to the terminal, but don't open a full-screen
ncurses interface.
This option is the default when exporting to a file.
.Pp
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,
.Fl 2
is usually a better choice.
.It Fl 2
Show 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.
.It Fl q , \-slow\-ui\-updates , \-fast\-ui\-updates
Change the UI update interval while scanning or importing.
.Nm
updates the screen 10 times a second by default (with
.Fl \-fast\-ui\-updates
), this can be decreased to once every 2 seconds with
.Fl q
or
.Fl \-slow\-ui\-updates .
This option can be used to save bandwidth over remote connections.
This option has no effect in combination with
.Fl 0 .
.It Fl \-enable\-shell , \-disable\-shell
Enable or disable shell spawning from the file browser.
This feature is enabled by default when scanning a live directory and disabled
when importing from file.
.It Fl \-enable\-delete , \-disable\-delete
Enable or disable the built-in file deletion feature.
This feature is enabled by default when scanning a live directory and disabled
when importing from file.
Explicitly disabling the deletion feature can work as a safeguard to prevent
accidental data loss.
.It Fl \-enable\-refresh , \-disable\-refresh
Enable or disable directory refreshing from the file browser.
This feature is enabled by default when scanning a live directory and disabled
when importing from file.
.It Fl r
Read-only mode.
When given once, this is an alias for
.Fl \-disable\-delete ,
when given twice it will also add
.Fl \-disable\-shell ,
thus ensuring that there is no way to modify the file system from within
.Nm .
.It Fl \-si , \-no\-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 (KiB, MiB, etc).
.It Fl \-disk\-usage , \-apparent\-size
Select whether to display disk usage (default) or apparent sizes.
Can also be toggled in the file browser with the 'a' key.
.It Fl \-show\-hidden , \-hide\-hidden
Show (default) or hide "hidden" and excluded files.
Can also be toggled in the file browser with the 'e' key.
.It Fl \-show\-itemcount , \-hide\-itemcount
Show or hide (default) the item counts column.
Can also be toggled in the file browser with the 'c' key.
.It Fl \-show\-mtime , \-hide\-mtime
Show or hide (default) the last modification time column.
Can also be toggled in the file browser with the 'm' key.
This option is ignored when not in extended mode, see
.Fl e .
.It Fl \-show\-graph , \-hide\-graph
Show (default) or hide the relative size bar column.
Can also be toggled in the file browser with the 'g' key.
.It Fl \-show\-percent , \-hide\-percent
Show (default) or hide the relative size percent column.
Can also be toggled in the file browser with the 'g' key.
.It Fl \-graph\-style Ar hash | half\-block | eighth\-block
Change the way that the relative size bar column is drawn.
Recognized values are
.Ar hash
to draw ASCII '#' characters (default and most portable),
.Ar half\-block
to use half-block drawing characters or
.Ar eighth\-block
to use eighth-block drawing characters.
Eighth-block characters are the most precise but may not render correctly in
all terminals.
.It Fl \-shared\-column Ar off | shared | unique
Set to
.Ar off
to disable the shared size column for directories,
.Ar shared
(default) to display shared directory sizes as a separate column or
.Ar unique
to display unique directory sizes as a separate column.
These options can also be cycled through in the file browser with the 'u' key.
.It Fl \-sort Ar column
Change the default column to sort on.
Accepted values are
.Ar disk\-usage
(the default),
.Ar name , apparent\-size , itemcount
or
.Ar mtime .
The latter only makes sense in extended mode, see
.Fl e .
.Pp
The column name can be suffixed with
.Li \-asc
or
.Li \-desc
to change the order to ascending or descending, respectively.
For example,
.Li \-\-sort=name\-desc
to sort by name in descending order.
.It Fl \-enable\-natsort , \-disable\-natsort
Enable (default) or disable natural sort when sorting by file name.
.It Fl \-group\-directories\-first , \-no\-group\-directories\-first
Sort (or not) directories before files.
.It Fl \-confirm\-quit , \-no\-confirm\-quit
Require a confirmation before quitting ncdu.
Can be helpful when you accidentally press 'q' during or after a very long scan.
.It Fl \-confirm\-delete , \-no\-confirm\-delete
Require a confirmation before deleting a file or directory.
Enabled by default, but can be disabled if you're absolutely sure you won't
accidentally press 'd'.
.It Fl \-color Ar off | dark | dark-bg
Set the color scheme.
The following schemes are recognized:
.Ar off
to disable colors,
.Ar dark
for a color scheme intended for dark backgrounds and
.Ar dark\-bg
for a variation of the
.Ar dark
color scheme that also works in terminals with a light background.
.Pp
The default is
.Ar off .
.El
.
.Sh CONFIGURATION
.Nm
can be configured by placing command-line options in
.Pa /etc/ncdu.conf
or
.Pa $HOME/.config/ncdu/config .
If both files exist, the system configuration will be loaded before the user
configuration, allowing users to override options set in the system
configuration.
Options given on the command line will override options set in the
configuration files.
The files will not be read at all when
.Fl \-ignore\-config
is given on the command line.
.Pp
The configuration file format is simply one command line option per line.
Lines starting with '#' are ignored.
A line can be prefixed with '@' to suppress errors while parsing the option.
Example configuration file:
.Bd -literal -offset indent
# Always enable extended mode
\-e

# Disable file deletion
\-\-disable\-delete

# Exclude .git directories
\-\-exclude .git

# Read excludes from ~/.ncduexcludes, ignore error if the file does not exist
@--exclude-from ~/.ncduexcludes
.Ed
.
.Sh KEYS
.Bl -tag -width Ds
.It ?
Open help + keys + about screen
.It up , down , j , k
Cycle through the items
.It right, enter, l
Open selected directory
.It left, <, h
Go to parent directory
.It n
Order by filename (press again for descending order)
.It s
Order by filesize (press again for descending order)
.It C
Order by number of items (press again for descending order)
.It a
Toggle between showing disk usage and showing apparent size.
.It M
Order by latest child mtime, or modified time (press again for descending
order).
Requires the
.Fl e
flag.
.It 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.
.It t
Toggle dirs before files when sorting.
.It 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.
.It u
Toggle display of the shared / unique size column for directories that share
hard links.
This column is only visible if the current listing contains directories with
shared hard links.
.It c
Toggle display of child item counts.
.It m
Toggle display of latest child mtime, or modified time.
Requires the
.Fl e
flag.
.It e
Show/hide 'hidden' or 'excluded' files and directories.
Be aware that even if 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.
.It i
Show information about the current selected item.
.It r
Refresh/recalculate the current directory.
.It b
Spawn shell in current directory.
.Pp
.Nm
determines your preferred shell from the
.Ev NCDU_SHELL
or
.Ev SHELL
environment variable (in that order), or calls
.Pa /bin/sh
if neither are set.
This allows you to also configure another command to be run when he 'b' key is
pressed.
For example, to spawn the
.Xr vifm 1
file manager instead of a shell, run
.Nm
as follows:
.Dl NCDU_SHELL=vifm ncdu
The
.Ev NCDU_LEVEL
environment variable is set or incremented before spawning the shell, allowing
you to detect if your shell is running from within
.Nm .
This can be useful to avoid nesting multiple instances, although
.Nm
itself does not (currently) warn about or prevent this situation.
.It q
Quit
.El
.
.Sh FILE FLAGS
Entries in the browser interface may be prefixed by a one\-character flag.
These flags have the following meaning:
.Bl -tag -width Ds
.It !
An error occurred while reading this directory.
.It \.
An error occurred while reading a subdirectory, so the indicated size may not
be correct.
.It <
File or directory is excluded from the statistics by using exclude patterns.
.It >
Directory is on another filesystem.
.It ^
Directory is excluded from the statistics due to being a Linux pseudo
filesystem.
.It @
This is neither a file nor a folder (symlink, socket, ...).
.It H
Same file was already counted (hard link).
.It e
Empty directory.
.El
.
.Sh EXAMPLES
To scan and browse the directory you're currently in, all you need is a simple:
.Dl ncdu
To scan a full filesystem, for example your root filesystem, you'll want to use
.Fl x :
.Dl ncdu \-x /
.Pp
Since scanning a large directory may take a while, you can scan a directory and
export the results for later viewing:
.Bd -literal -offset indent
ncdu \-1xO export.ncdu /
# ...some time later:
ncdu \-f export.ncdu
.Ed
To export from a cron job, make sure to replace
.Fl 1
with
.Fl 0
to suppress unnecessary progress output.
.Pp
You can also export a directory and browse it once scanning is done:
.Dl ncdu \-co\- | tee export.json.zst | ./ncdu \-f\-
.Pp
To scan a system remotely, but browse through the files locally:
.Dl ssh user@system ncdu \-co\- / | ./ncdu \-f\-
Remote scanning and local viewing has two major advantages when
compared to running
.Nm
directly on the remote system: You can browse through the scanned directory on
the local system without any network latency, and
.Nm
does not keep the entire directory structure in memory when exporting, so this
won't consume much memory on the remote system.
.
.Sh SEE ALSO
.Xr du 1 ,
.Xr tree 1 .
.Pp
.Nm
has a website:
.Lk https://dev.yorhel.nl/ncdu
.
.Sh AUTHORS
Written by
.An Yorhel Aq Mt projects@yorhel.nl
.
.Sh BUGS
Directory hard links and firmlinks (MacOS) are not supported.
They are not detected as being hard links and will thus get scanned and counted
multiple times.
.Pp
Some minor glitches may appear when displaying filenames that contain multibyte
or multicolumn characters.
.Pp
The unique and shared directory sizes are calculated based on the assumption
that the link count of hard links does not change during a filesystem scan or
in between refreshes.
If this does happen, for example when a hard link is deleted, then these
numbers will be very much incorrect and a full refresh by restarting ncdu is
needed to get correct numbers again.
.Pp
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.
When deleting or refreshing items in a directory with a clipped size, the
resulting sizes will be incorrect.
Likewise, item counts are stored in a 32-bit integer, so will be incorrect in
the unlikely event that you happen to have more than 4 billion items in a
directory.
.Pp
Please report any other bugs you may find at the bug tracker, which can be
found on the web site at
.Lk https://dev.yorhel.nl/ncdu