duc-nox(1) index, query and graph disk usage


duc-nox <subcommand> [options]


Duc is a collection of tools for inspecting and visualizing disk usage.

Duc maintains an indexed database of accumulated sizes of directories of your file system, and allows you to query this database with some tools, or create graphs to show you where your bytes are.

Duc scales quite well, it has been tested on systems with more then 500 million files and several petabytes of storage.


Duc comes with a command line tool called `duc-nox`, which is used to create,
maintain and query the disk usage database.
run `duc-nox help` to get a list of available commands. `duc-nox help <subcommand>` describes the usage of a specific subcommand. Run `duc-nox help --all` for an extensive list of all commands and their options.

Duc allows any option to be placed either on the command line or in a configuration file. Options on the command line are preceded by a double-leading-dash (`--option`), some options have a corresponding short option which can be used as well with a single leading dash. (`-o`)

At startup duc tries to read its configuration from three locations in this particular order: `/etc/ducrc`, `~/.ducrc` and `./.ducrc`.

A configuration file consists of sections and parameters. The section names correspond to the duc-nox subcommands for which the parameters in that section apply. A section begins with the name of the section in square brackets and continues until the next section begins.Sections contain parameters, one per line, which consist of a single option name for boolean flags, or a option name and a value for options which take a value. See the EXAMPLES section for an example of the configuration file format.


Duc needs an index file of the file system before it is able to show any
To create the index, run the `duc-nox index` command. For example, to create an index of your home directory run `duc-nox index ~`

    $ duc-nox index /usr
    Skipping lost+found: Permission denied
    Indexed 333823 files and 48200 directories, (35.0GB total)
    in 1 seconds
The default location of the database is `$HOME/.duc.db`. To use a different database location, use the DUC_DATABASE environment variable or specify the database location with the --database argument.

You can run `duc- index` at any time later to rebuild the index.

By default Duc indexes all directories it encounters during file system traversal traversal, including special file systems like /proc and /sys, and network file systems like NFS or Samba mounts. There are a few options to select what parts of your filesystem you want to include or exclude from the scan, check the documentation below for --exclude, --fs-exclude and --fs-include for more details.


Duc has various subcommands for querying or exploring the index:
  • `duc-nox info` shows a list of available directory trees in the database, and the time and date of the last scan.
  • `duc-nox ls` lists all files and directories under the given path on the console.
  • `duc-nox ui` runs a ncurses based console user interface for exploring the file system usage


This section list all available subcommands and describes their usage and options. Global options These options apply to all Duc subcommands:
  • --debug: increase verbosity to debug level
  • -h, --help: show help
  • -q, --quiet: quiet mode, do not print any warning
  • -v, --verbose: increase verbosity
  • --version: output version information and exit

duc-nox help Options for command `duc-nox help [options]`:

  • -a, --all: show complete help for all commands

duc- index The 'index' subcommand performs a recursive scan of the given paths on the filesystem and calculates the inclusive size of all directories. The results are written to the index, and can later be queried by one of the other duc-nox tools.

Options for command `duc-nox index [options] PATH ...`:

  • -b, --bytes: show file size in exact number of bytes
  • -d, --database=VAL: use database file VAL
  • -e, --exclude=VAL: exclude files matching VAL
  • -H, --check-hard-links: count hard links only once. if two or more hard links point to the same file, only one of the hard links is displayed and counted
  • -f, --force: force writing in case of corrupted db
  • --fs-exclude=VAL exclude file system type VAL during indexing. VAL is a comma separated list of file system types as found in your systems fstab, for example ext3, ext4,dosfs
  • --fs-include=VAL include file system type VAL during indexing. VAL is a comma separated list of file system types as found in your systems fstab, for example ext3,ext4,dosfs
  • --hide-file-names: hide file names in index (privacy). the names of directories will be preserved, but the names of the individual files will be hidden
  • -m, --max-depth=VAL: limit directory names to given depth. when this option is given duc-nox will traverse the complete file system, but will only the first VAL levels of directories in the database to reduce the size of the index
  • -x, --one-file-system: skip directories on different file systems
  • -p, --progress: show progress during indexing
  • --uncompressed: do not use compression for database. Duc enables compression if the underlying database supports this. This reduces index size at the cost of slightly longer indexing time

duc-nox info Options for command `duc-nox info [options]`:

  • -a, --apparent: show apparent instead of actual file size
  • -b, --bytes: show file size in exact number of bytes
  • -d, --database=VAL: select database file to use [~/.duc.db]

duc-nox ls The 'ls' subcommand queries the duc database and lists the inclusive size of all files and directories on the given path. If no path is given the current working directory is listed.

Options for command `duc-nox ls [options] [PATH]`:

  • -a, --apparent: show apparent instead of actual file size
  • --ascii: use ASCII characters instead of UTF-8 to draw tree
  • -b, --bytes: show file size in exact number of bytes
  • -F, --classify: append file type indicator (one of */) to entries
  • -c, --color: colorize output (only on ttys)
  • --count show number of files instead of file size
  • -d, --database=VAL: select database file to use [~/.duc.db]
  • --dirs-only: list only directories, skip individual files
  • -l, --levels=VAL: traverse up to ARG levels deep [4]
  • -R, --recursive: list subdirectories in a recursive tree view

duc-nox xml Options for command `duc-nox xml [options] [PATH]`:

  • -d, --database=VAL: select database file to use [~/.duc.db]
  • -x, --exclude-files: exclude file from xml output, only include directories
  • -s, --min_size=VAL: specify min size for files or directories

duc-nox cgi Options for command `duc-nox cgi [options] [PATH]`:

  • -a, --apparent: Show apparent instead of actual file size
  • -b, --bytes: show file size in exact number of bytes
  • --count show number of files instead of file size
  • --css-url=VAL: url of CSS style sheet to use instead of default CSS
  • -d, --database=VAL: select database file to use [~/.duc.db]
  • -l, --levels=VAL: draw up to ARG levels deep [4]
  • --list: generate table with file list
  • --tooltip: enable tooltip when hovering over the graph. enabling the tooltip will cause an asynchronous HTTP request every time the mouse is moved and can greatly increas the HTTP traffic to the web server

duc-nox ui The 'ui' subcommand queries the duc database and runs an interactive ncurses utility for exploring the disk usage of the given path. If no path is given the current working directory is explored.

The following keys can be used to navigate and alter the file system:

    up, pgup, j:     move cursor up
    down, pgdn, k:   move cursor down
    left, backspace: go up to parent directory (..)
    right, enter:    descent into selected directory
    a:               toggle between actual and apparent disk usage
    b:               toggle between exact and abbreviated sizes
    c:               toggle between file size and file count
    h:               show help. press 'q' to return to the main
    q, escape:       quit
Options for command `duc-nox ui [options] [PATH]`:
  • -a, --apparent: show apparent instead of actual file size
  • -b, --bytes: show file size in exact number of bytes
  • --count show number of files instead of file size
  • -c, --color: colorize output
  • --no-color do not use colors on terminal output
  • -d, --database=VAL: select database file to use [~/.duc.db]


The `duc-nox` binary has support for a rudimentary CGI interface,
currently only tested with apache.
The CGI interface generates a simple HTML page with a list of indexed directories. If the option `--list` is given, a list of top sized files/dirs is written.

Configuration is done by creating a simple shell script as .cgi in a directory which is configured for CGI execution by your web server (usually `/usr/lib/cgi-bin`). The shell script should simply start duc-nox, and pass the location of the database to navigate.

An example duc.cgi script would be

    /usr/bin/duc-nox cgi -d /home/jenny/.duc.db
    * Make sure the database file is readable by the user (usually
    * Debugging is best done by inspecting the web server's error log
    * Make sure the .cgi script has execute permissions
      (`chmod +x duc.cgi`)
Some notes:
  • The HTML page is generated with a simple embedded CSS style sheet. If the style is not to your liking you can provide an external CSS url with the --css-url option which will then be used instead of the embedded style definition.
  • Add the option --list to generate a table of top sized files and directories in the HTML page.

The current CGI configuration is not very flexible, nor secure. It is not advised to run the CGI from public reachable web servers, use at your own risk.


The concepts of 'file size' and 'disk usage' can be a bit confusing. Files on disk have an apparent size, which indicates how much bytes are in the file from the users point of view; this is the size reported by tools like `ls -l`.
The apparent size can be any number, from 0 bytes up to several TB.
The actual number of bytes which are used on the filesystem to store the file can differ from this apparent size for a number of reasons: disks store data in blocks, which cause files to always take up a multiple of the block size, files can have holes ('sparse' files), and other technical reasons. This number is always a multiple of 512, which means that the actual size used for a file is almost always a bit more then its apparent size.

Duc has two modes for counting file sizes:

- `apparent size`: this is the size as reported by `ls`. This number indicates the file length, which is usually smaller then the actual disk usage.

- `actual size`: this is the size as reported by `du` and `df`. The actual file size tells you how much disk is actually used by a file, and is always a multiple of 512 bytes.

The default mode used by duc-nox is to use the 'actual size'. Most duc-nox commands to report disk usage (`duc-nox ls`, etc) have an option to change between these two modes (usually the `-a`).


Index the /usr directory, writing to the default database location ~/.duc.db:

    $ duc-nox index /usr
List all files and directories under /usr/local, showing relative file sizes in a graph:

    $ duc-nox ls -Fg /usr/local
      4.7G lib/                 [+++++++++++++++++++++++++++++++++++++]
      3.1G share/               [+++++++++++++++++++++++++            ]
      2.7G src/                 [+++++++++++++++++++++                ]
    814.9M bin/                 [++++                                 ]
    196.6M include/             [+                                    ]
     66.6M x86_64-w64-mingw32/  [                                     ]
     59.9M local/               [                                     ]
     38.8M i686-w64-mingw32/    [                                     ]
     20.3M sbin/                [                                     ]
     13.6M lib32/               [                                     ]
     13.3M libx32/              [                                     ]
or use the -R
options for the tree view:

    $ duc-nox ls -RF /etc/logcheck
     24.0K `+- ignore.d.server/
      4.0K  |  `+- hddtemp 
      4.0K  |   |- ntpdate 
      4.0K  |   |- lirc 
      4.0K  |   |- rsyslog 
      4.0K  |   `- libsasl2-modules 
      8.0K  |- ignore.d.workstation/
      4.0K  |   `- lirc 
      8.0K  `- ignore.d.paranoid/
      4.0K      `- lirc 
The following sample configuration file defines default parameters for the `duc-nox ls` command and defines a global option to configure the database path which is used by all subcommands

    database /var/cache/duc.db


What does the error 'Database version mismatch mean?

The layout of the index database sometimes changes when new features are implemented. When you get this error you have probably upgraded to a newer version. Just remove the old database file and rebuild the index.

Duc crashes with a segmentation fault, is it that buggy?

By default Duc uses the Tokyocabinet database backend. Tokyocabinet is pretty fast, stores the database in a single file and has nice compression support to keep the database small. Unfortunately, it is not always robust and sometimes chokes on corrupt database files. Try to remove the database and rebuild the index. If the error persists contact the authors.


At startup duc-nox tries to read its configuration from three locations in this particular order: `/etc/ducrc`, `~/.ducrc` and `./.ducrc`.

Duc mainains an index of scanned directories, which defaults to ~/.duc.db. All tools take the -d/--database option to override the database path.


Other contributers can be found in the Git log at GitHub.

This manual page was adapt by Herbert Parentes Fortes Neto <[email protected]> from the duc manpage of the duc project for duc-nox package of the Debian project (but may be used by others)


Duc is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 dated June, 1991. Duc is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.