[3745] | 1 | .\"------------------------------------------------------------
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| 2 | .\" Id - set Rv,revision, and Dt, Date using rcs-Id tag.
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| 3 | .de Id
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| 4 | .ds Rv \\$3
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| 5 | .ds Dt \\$4
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| 6 | ..
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| 7 | .Id $Id: mgintro++.1 16583 2008-07-29 10:20:36Z davidb $
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| 8 | .\"------------------------------------------------------------
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| 9 | .ds r \&\s-1MG\s0
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| 10 | .if n .ds - \%--
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| 11 | .if t .ds - \(em
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| 12 | .\"------------------------------------------------------------
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| 13 | .am SS
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| 14 | .LP
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| 15 | ..
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| 16 | .\"------------------------------------------------------------
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| 17 | .TH MGINTRO++ 1 \*(Dt CITRI
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| 18 | .\"--------------------------------------------------------------
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| 19 | .SH NAME
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| 20 | mgintro++ \- extended introduction to the MG system
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| 21 | .\"-------------------------------------------------------------
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| 22 | .SH DESCRIPTION
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| 23 | This manual assumes the reader has already read
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| 24 | .BR mgintro (1).
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| 25 | .\"-------------------------------------------------------------
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| 26 | .SS Creating Different Databases
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| 27 | If a user wants to build databases other than for some
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| 28 | predefined ones, such as "alice", "davinci", "mailfiles", "allfiles",
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| 29 | then the user has a couple of choices.
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| 30 | Ultimately (s)he must produce a text file with control-Bs
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| 31 | terminating the documents.
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| 32 | To do this one can produce one or more such files, or write a
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| 33 | "get" command (typically in the form of a script or c program).
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| 34 | .\"-------------------------------------------------------------
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| 35 | .SS Using Input Files for mgbuild
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| 36 | If you don't want to write a "get" script and just want to use
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| 37 | one or more text files as input, then you must first generate
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| 38 | the file with control-Bs. For a simple example, you could take
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| 39 | any text file(s) such as "test1.txt" and "test2.txt", and use
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| 40 | .BR vi (1)
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| 41 | to insert control-Bs by typing "control-V b".
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| 42 | Next you should create a file with "set" statements
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| 43 | in the following form:
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| 44 | .PP
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| 45 | .IP
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| 46 | \fBset pipe = 0 # do not use pipe - use file instead
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| 47 | .br
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| 48 | \fBset input_files = 'test1.txt test2.txt'
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| 49 | .LP
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| 50 | Let's call this file, "build_options".
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| 51 | Now issue the command:
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| 52 | .IP
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| 53 | .B mgbuild -s build_options test
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| 54 | .LP
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| 55 | This should build a database called "test" in the $MGDATA directory,
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| 56 | based on the source data of "test1.txt" and "test2.txt".
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| 57 | The build_options file is simply sourced by
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| 58 | .BR mgbuild (1)
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| 59 | after it has set up its variables.
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| 60 | Therefore, any settings one makes in the
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| 61 | build_options file will override the standard settings.
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| 62 | See
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| 63 | .BR mgbuild (1)
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| 64 | for more information.
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| 65 | .\"-------------------------------------------------------------
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| 66 | .SS Writing A Get Program
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| 67 | Instead of using files as input, it is often more convenient to
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| 68 | write a "get" program. This program is called by
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| 69 | .BR mgbuild (1)
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| 70 | to get the text data with control-Bs as document terminators.
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| 71 | It should take three options:
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| 72 | .br
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| 73 | (i) -init; (ii) -text; (iii) -cleanup.
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| 74 | .br
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| 75 | Get will be called with "init" first and with "cleanup" at the end.
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| 76 | It will call get with "text" when it wants the text and it should
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| 77 | write the text to stdout.
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| 78 | .br
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| 79 | See
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| 80 | .BR mg_get (1)
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| 81 | for an example.
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| 82 | .\"-------------------------------------------------------------
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| 83 | .SS Regular Builds
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| 84 | The MG system provides a static database;
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| 85 | there are no update commands.
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| 86 | So if one wants to keep one's database reasonably up-to-date
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| 87 | then one can have this done automatically on a regular basis by
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| 88 | .BR cron (1).
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| 89 | A crontab file can be created using:
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| 90 | crontab -e
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| 91 | A crontab file contains lines of the form:
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| 92 | .nf
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| 93 | .IP
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| 94 | \fBminute hour day-of-month month day-of-week shell-command.
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| 95 | .LP
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| 96 | .fi
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| 97 | See
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| 98 | .BR crontab (1)
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| 99 | for more information.
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| 100 | .nf
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| 101 | An example crontab entry is:
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| 102 | .IP
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| 103 | \fB15 02 * * * mgbuild allfiles >$MGDATA/allfiles/allfiles.log 2>&1
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| 104 | .LP
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| 105 | .fi
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| 106 | This will build up the mg database for "allfiles", your mail in
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| 107 | the folders, every morning at 2:15am.
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| 108 | .\"
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| 109 | .\"-------------------------------------------------------------
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| 110 | .SS Command Structure
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| 111 | There are 22 commands that make up the mg system. However,
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| 112 | a user may only need to be aware of a few:
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| 113 | .BR mgbuild (1),
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| 114 | .BR mgquery (1),
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| 115 | and perhaps
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| 116 | .BR mg_get (1).
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| 117 | Many of the commands are called by
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| 118 | .BR mgbuild(1).
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| 119 | The commands can be broken up into a hierarchy.
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| 120 | .PP
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| 121 | --------------------------------------
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| 122 | .br
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| 123 | MG--+--image compression
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| 124 | | |
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| 125 | | +--mgbilevel
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| 126 | | |
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| 127 | | +--mgfelics
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| 128 | | |
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| 129 | | +--mgtic
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| 130 | | |
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| 131 | | +--mgticbuild
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| 132 | | |
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| 133 | | +--mgticdump
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| 134 | | |
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| 135 | | +--mgticprune
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| 136 | | |
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| 137 | | +--mgticstat
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| 138 | |
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| 139 | +--text
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| 140 | |
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| 141 | +--compression
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| 142 | | |
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| 143 | | +--mg_passes -T1
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| 144 | | |
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| 145 | | +--mg_passes -T2
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| 146 | | |
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| 147 | | +--mg_compression_dict
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| 148 | | |
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| 149 | | +--mg_fast_comp_dict
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| 150 | |
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| 151 | +--indexing
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| 152 | | |
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| 153 | | +--mg_passes -N1
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| 154 | | |
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| 155 | | +--mg_passes -N2
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| 156 | | |
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| 157 | | +--mg_perf_hash_build
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| 158 | | |
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| 159 | | +--mg_invf_dict
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| 160 | | |
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| 161 | | +--mg_invf_rebuild
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| 162 | |
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| 163 | +--weights
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| 164 | | |
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| 165 | | +--mg_weights_build
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| 166 | |
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| 167 | +--query
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| 168 | | |
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| 169 | | +--mgquery
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| 170 | |
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| 171 | +--tools
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| 172 | |
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| 173 | +--mg_invf_dump
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| 174 | |
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| 175 | +--mg_text_estimate
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| 176 | |
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| 177 | +--mgdictlist
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| 178 | |
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| 179 | +--mgstat
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| 180 | .br
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| 181 | --------------------------------------
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| 182 | .PP
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| 183 | .nf
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| 184 | .BR mgbuild (1)
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| 185 | calls the following commands:
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| 186 | .RS
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| 187 | .BR mg_passes (1), mg_compression_dict (1)
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| 188 | .BR mg_perf_hash_build (1), mg_invf_dict (1), mg_invf_rebuild (1)
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| 189 | .BR mg_weights_build (1)
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| 190 | .RE
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| 191 | .fi
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| 192 | .\"--------------------------------------------
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| 193 | .SH SEE ALSO
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| 194 | .BR mgintro (1),
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| 195 | .BR mgbuild (1),
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| 196 | .BR mg_get (1)
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| 197 | .br
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| 198 | "Guide To The \*r System", in Appendix A of the book:
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| 199 | .PP
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| 200 | .RS
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| 201 | .nf
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| 202 | Ian H. Witten, Alistair Moffat, and Timothy C. Bell
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| 203 | .I "Managing Gigabytes: Compressing and Indexing Documents and Images"
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| 204 | Van Nostrand Reinhold
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| 205 | 1994
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| 206 | xiv + 429 pages
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| 207 | US$54.95
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| 208 | ISBN 0-442-01863-0
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| 209 | Library of Congress catalog number TA1637 .W58 1994.
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| 210 | .fi
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| 211 | .RE
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| 212 |
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