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

## SYNOPSIS

`duc` <subcommand> [options]


## DESCRIPTION

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
fancy sunburst 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. 


## USAGE

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


## CREATING THE INDEX

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

    $ duc 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.


## QUERYING THE INDEX

Duc has various subcommands for querying or exploring the index:

* `duc info` shows a list of available directory trees in the database, and the time
  and date of the last scan.

* `duc ls` lists all files and directories under the given path on the console.

* `duc ui` runs a ncurses based console user interface for exploring the file
  system usage

* `duc gui` starts a graphical (X11) interface representing the file system in
  a sunburst graph. Click on a directory to redraw the graph from the
  perspective of the selected directory. Click in the center of the graph to go
  up one directory in the tree.


## OPTIONS

This section list all available subcommands and describes their usage and options.

>>>> run duc help --all for a list of all subcommands and options.


## CGI INTERFACING

The `duc` 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, and shows a clickable graph for navigating the file
system. If the option `--list` is given, a list of top sized files/dirs is also
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, and pass the
location of the database to navigate.

An example duc.cgi script would be

    #!/bin/sh
    /usr/local/bin/duc cgi -d /home/jenny/.duc.db

* Make sure the database file is readable by the user (usually www-data)
* 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.


## A NOTE ON FILE SIZE AND DISK USAGE

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 is to use the 'actual size'. Most duc commands to
report disk usage (`duc ls`, `duc graph`, `duc gui`, etc) have an option to
change between these two modes (usually the `-a`), in the gui tool use the 'a'
key to toggle.


## EXAMPLES


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

    $ duc index /usr

List all files and directories under /usr/local, showing relative file sizes
in a graph:

    $ duc 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 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 

Start the graphical interface to explore the file system using sunburst graphs:

    $ duc gui /usr

Generate a graph of /usr/local in .png format:

    $ duc graph -o /tmp/usr.png /usr


The following sample configuration file defines default parameters for the `duc
ls` and `duc gui` commands and defines a global option to configure the database
path which is used by all subcommands
 
    [global]
    database /var/cache/duc.db
 
    [ls]
    recursive
    classify
    color
    
    [gui]
    fuzz 0.7
    palette rainbow
    levels 4

    [ui]
    color

## FREQUENTLY ASKED QUESTIONS

* 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.

## FILES

At startup duc 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.


## AUTHORS

* Ico Doornekamp <duc@zevv.nl>
* John Stoffel <john@stoffel.org>

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


## LICENSE

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.

