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214 lines
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
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<title>The DICT Project LG #33</title>
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<H4>
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"Linux Gazette...<I>making Linux just a little more fun!</I>"
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</H4>
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<P> <HR> <P>
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<center>
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<h1><font color="maroon">DICT and Word Inspector</font></h1>
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<h4>By <a href="mailto: layers@marktwain.net">Larry Ayers</a></h4>
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</center>
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<P> <HR> <P>
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<center><h3>Introduction</h3></center>
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<p>Access to an on-line dictionary has been possible for several years now due
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to the Webster TCPIP protocol. Webster is useful but the number of servers
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has been on the decline, and the protocol itself is limited by its dependence
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on a single dictionary database. Rik Faith, a programmer responsible for many
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of the essential-but-taken-for-granted Linux utilities, has created a new,
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more flexible protocol known as DICT. DICT is another TCPIP protocol (usable
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either over a network or on a local machine) which provides access to any
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number of dictionary databases. Local access is provided by a client program
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called <i>dict</i> which contacts the <i>dictd</i> server daemon.
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<i>Dictd</i> then searches the available databases and makes any hits
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available to <i>dict</i>, which pipes its output to the default pager on the
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local machine (usually either <i>more</i>, <i>less</i>, or <i>most</i>). Net
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access is available from several servers, including the home
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<a href="http://www.dict.org">DICT</a> site. Looking up words while on-line
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frees the user from needing to install and run the <i>dictd</i> and
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<i>dict</i> client and server programs (as well as having to make room for the
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bulky databases on a local disk), but if you have the disk space it's
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convenient to have the service available at any time.
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<p>The <i>dictd</i> and <i>dict</i> programs are licensed under the GPL, so
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naturally they are set up to use freely available word databases.
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<center><h3>Installing The DICT Distribution Locally</h3></center>
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<p>DICT is a typical Unix-style command-line set of programs. GUI-fans will
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regret the absence of a graphical interface, but the glass is really
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half-full. Due to the absence of oft-troublesome GUI toolkit dependencies,
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the source for the client and server programs should compile easily. Toolkits
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come and go, but applications written with a simple console interface can
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easily be adapted to whatever the future toolkit du jour might be. There are
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numerous programmers who lack the time or inclination to develop Linux
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utilities from scratch, but welcome the opportunity to write GUI front-ends to
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console programs (see the Word Inspector section below).
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<p>
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Compiling and installing <i>dictd</i> and <i>dict</i> isn't difficult, but to
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make use of them the word databases need to be downloaded and installed. Here
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is a list of the free databases which are currently available from the
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<a href="ftp://ftp.dict.org/pub/dict/pre/">DICT</a> FTP site:
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<ul>
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<li>A 1913 edition of Webster's Revised Unabridged Dictionary
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<li>The Free On-Line Dictionary of Computing
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<li>Eric Raymond's Jargon File
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<li>The WordNet database
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<li>Easton's 1897 Bible Dictionary
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<li>Hitchcock's Bible Names Dictionary
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<li>The Elements (physical elements)
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<li>U.S Gazetteer (1990)
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<li>The 1995 CIA World Factbook
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</ul>
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<p>All of these files and their indices will occupy about thirty-one megabytes
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of disk space, roughly the same amount as the WordNet dictionary files alone.
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The DICT data-files are compressed with a variant of <i>gzip</i> called
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<i>dictzip</i>, also written by Rik Faith. <i>Dictzip</i> adds extra header
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information to a compressed file which allows pseudo-random access to the
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file. When the <i>dictd</i> server processes a request for a word it looks
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first in the various index files. These files (which are human-readable)
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are just simple lists with the location of each word within the compressed
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dictionary file. <i>Dictd</i> is able to use this information to uncompress
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just the single 64-kb. block of data which contains the word-entry. This
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greatly speeds up access, as the entire dictionary file doesn't need to be
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uncompressed and subsequently re-compressed for each transaction. Files
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compressed with <i>dictzip</i> can be recognized by the <i>*.dz</i> suffix.
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<p>Although <i>dictzip</i> doesn't compress quite as tightly as <i>gzip</i>,
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the added advantage of the header information (at least for the sort of access
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<i>dictd</i> needs) is a compensation. The above-listed dictionary files
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would need nearly seventy-five megabytes of disk space if they weren't
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compressed.
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<center><h3>Comparison With WordNet</h3></center>
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<p>In issue 27 of the Gazette, (April, 1998) I wrote about another
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dictionary-database system called WordNet. In order to access a DICT database
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the <i>dict</i> server must be running which communicates with <i>dict</i>
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client programs, whereas WordNet isn't a client-server program; the small
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<i>wn</i> program searches the database indices directly. The upshot is that
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WordNet uses less memory than a DICT system, but since WordNet databases
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aren't compressed they occupy more disk space than the specially compressed
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DICT files. DICT files contain more words (along with etymologies, which
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WordNet lacks) and can be supplemented with new files in the future, but DICT
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lacks WordNet's powerful thesaurus and lexical usage capabilities. Another
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factor to consider is that development of WordNet has ceased, whereas DICT is
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still being improved and the chances of its continued development seem likely.
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Additionally, DICT can use the WordNet data-files in a compressed format.
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<center><h3>Configuration</h3></center>
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<p>Sample configuration files are included with the DICT distribution. The
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file <kbd>/etc/dictd.conf</kbd> should contain the location of your local
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dictionary files in this format:<br>
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<pre><kbd>
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database web1913 { data "/mt/dict/web1913.dict.dz"
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index "/mt/dict/web1913.index" }
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database jargon { data "/mt/dict/jargon.dict.dz"
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index "/mt/dict/jargon.index" }
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</kbd></pre>
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<p>The <i>dict</i> client needs to know where the server is; if a local
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server is used a simple <kbd>~/.dictrc</kbd> file containing this line will
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work:<br>
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<pre><kbd>
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server localhost
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</kbd></pre>
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<p>If both <kbd>~.dictrc</kbd> and <kbd>/etc/dict.conf</kbd> are missing the
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<i>dict </i> client program will first attempt to access the www.dict.org
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web-server; if that fails it will try some alternate sites. To prevent these
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attempts (when running a local <i>dictd</i> server) just use the above
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<kbd>~/.dictrc</kbd> file.
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<center><h3>Drawbacks</h3></center>
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<p><i>Dictd</i> might not be a service which you would want to run all of the
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time. Though not a large executable, it uses a significant amount of memory,
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typically four to five megabytes. I surmise that the daemon reads the
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dictionary index-files into memory when it starts up and keeps them there.
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This premise also would explain why the word look-ups are so speedy. Memory
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access is much faster than disk access, and once the daemon determines from
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the index which sixty-four kilobyte block holds the desired information it can
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quickly decompress that small chunk of the dictionary file and serve up the
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word information. I've found that starting <i>dictd</i> while writing or
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whenever I become curious about word-usage and killing the daemon at other
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times works well.
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<center><h3>Word Inspector</h3></center>
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<p>Scott W. Gifford has written a nice graphical front-end to the <i>dict</i>
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client program called Word Inspector. Here's a screenshot of the initial
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window:<br>
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<p><img alt="Word Inspector Main Window" src="./gx/ayers/inspect1.gif">
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<p>And here is one showing the output window:<br>
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<p><img alt="Word Inspector Output Window" src="./gx/ayers/inspect2.gif">
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<p>In the README file accompanying Word Inspector Scott Gifford suggests
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setting up the application with several different window-manager menu-items.
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Running <kbd>wordinspect --define --clipboard</kbd> will bring up a Word
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Inspector output window (as shown in the second screenshot) with the contents
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of the current X primary selection as the input. Alternatively,
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<kbd>wordinspect --search --clipboard</kbd> will cause the initial window to
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appear with the X primary selection already shown in the entry field, and
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running just plain <kbd>wordinspect</kbd> will bring up an empty initial
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window, so that a word can be typed in which isn't a mouse-selection.
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These three commands could be set up in a submenu stemming from a top-level
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Word Inspector menu-item.
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<p>Word Inspector makes good use of right-mouse-button pop-up menus.
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Right-clicking on any word in a definition pops up a menu allowing you to
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either open a search (initial) window with the selected word already filled
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in, or open a definition window for the word. Highlighting a series of words
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with the mouse, then right-clicking, will enable the same behavior for
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phrases.
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<p>The source of the current version of Word Inspector is this
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<a href="http://www.tir.com/~sgifford/wordinspect/">web-site</a>. The GTK
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toolkit is required for compilation, with version 1.06 recommended.
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<!-- hhmts start -->
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Last modified: Mon 28 Sep 1998
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<!-- hhmts end -->
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<!--===================================================================-->
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<P> <hr> <P>
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<center><H5>Copyright © 1998, Larry Ayers <BR>
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Published in Issue 33 of <i>Linux Gazette</i>, October 1998</H5></center>
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