| 1 | ###########################################################################
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| 2 | #
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| 3 | # help.mg.src -- Source for the help command
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| 4 | # Copyright (C) 1994 Neil Sharman
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| 5 | #
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| 6 | # This program is free software; you can redistribute it and/or modify
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| 7 | # it under the terms of the GNU General Public License as published by
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| 8 | # the Free Software Foundation; either version 2 of the License, or
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| 9 | # (at your option) any later version.
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| 10 | #
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| 11 | # This program is distributed in the hope that it will be useful,
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| 12 | # but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | # GNU General Public License for more details.
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| 15 | #
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| 16 | # You should have received a copy of the GNU General Public License
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| 17 | # along with this program; if not, write to the Free Software
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| 18 | # Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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| 19 | #
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| 20 | # @(#)help.mg.src 1.8 21 Mar 1994
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| 21 | #
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| 22 | ###########################################################################
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| 23 | #
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| 24 | # The help file for mgquery.
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| 25 | # Lines starting with '#' are treated as comments and are discarded when
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| 26 | # the 'help.mg.h' file is produced
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| 27 | #
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| 28 | ###########################################################################
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| 29 |
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| 30 | HELP for mgquery
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| 31 | ================================
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| 32 |
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| 33 | The text is a summary of the information in the "mgquery" manual pages.
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| 34 |
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| 35 | The input to 'mgquery' consists of a series of input lines. The backslash
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| 36 | character ("\") is used at the end of lines to indicate that input
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| 37 | continues on the next line.
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| 38 |
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| 39 | Input lines on which the first character is a dot (".") are commands to
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| 40 | the mgquery program. Input lines that do not start with a dot are queries.
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| 41 |
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| 42 | A query consists of two parts. One part is a boolean or ranked query that
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| 43 | identifies documents. The second part is a post-processing pattern matching
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| 44 | operation. Any text between the first speech mark (") and the last speech
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| 45 | mark is considered to the a post-processing pattern.
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| 46 |
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| 47 |
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| 48 | The following command are available :-
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| 49 |
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| 50 | .help - displays this text.
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| 51 | .quit - quits the program.
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| 52 | .set name value - sets parameter "name" to "value" . If the parameter
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| 53 | is a boolean parameter and value is omitted the
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| 54 | parameter will be inverted (i.e. if it is true it
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| 55 | will change to false, if it is false it will change
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| 56 | to true).
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| 57 | .unset name - deletes parameter "name"
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| 58 | .reset - sets all the parameters to their initial state.
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| 59 | .display - displays the values of all the current parameters.
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| 60 | .push - pushes the current parameters on to a stack.
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| 61 | .pop - destroys the current parameters and pops a new set
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| 62 | of parameters off the stack.
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| 63 | .output arg - This is used to specify where to send the documents.
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| 64 | Arg may one be of the following:
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| 65 | > filename : Send output to the specified file.
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| 66 | >> filename : Append output to the specified file.
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| 67 | | command : The output is piped into command,
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| 68 | which is executed by sh.
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| 69 | .input arg - This is used to specify where input comes from.
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| 70 | Arg may one be of the following:
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| 71 | < filename : Get the input from the specified
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| 72 | file.
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| 73 | | command : The input comes from the standard
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| 74 | output of command, which is executed
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| 75 | by sh.
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| 76 |
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| 77 | On startup the mgquery program reads from the file .mgrc a sequence
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| 78 | of commands (NOTE: The .mgrc file may not contain any queries). mgquery
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| 79 | first looks for .mgrc in the current directory and then in the users home
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| 80 | directory. Lines starting with a '#' in the .mgrc file are considered to
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| 81 | be comments and are ignored.
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| 82 |
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| 83 | The following parameters (used in the .set and .unset commands) are
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| 84 | predefined and have special significance :-
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| 85 |
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| 86 | accumulator_method = `array'
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| 87 | This parameter is used during ranking, and specifies how the
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| 88 | weight for each document should be accumulated. The following
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| 89 | methods are available `array', `splay_tree', `hash_table', and
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| 90 | `list'.
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| 91 |
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| 92 | briefstats = `off'
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| 93 | This is a boolean parameter that determines whether the the
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| 94 | totals for disk, memory and time usage statistics will be
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| 95 | displayed. at the end of each query.
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| 96 | NOTE: this takes precedence over the parameters "diskstats",
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| 97 | "memstats" and "timestats". This parameter may take the values
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| 98 | `yes', `no', `true', `false', `on' or `off'.
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| 99 |
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| 100 | buffer = `1048576'
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| 101 | When the documents are being read in they are read into a
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| 102 | buffer of this size and then displayed from this buffer. If
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| 103 | the documents are larger than this buffer the buffer is
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| 104 | expanded automatically. Having a large buffer gives a very
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| 105 | slight performance improvement because it allows the order of
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| 106 | disk operations to be optimised. The buffer size is measured
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| 107 | in bytes.
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| 108 |
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| 109 | diskstats = `off'
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| 110 | This is a boolean parameter that determines whether the disk
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| 111 | usage statistics for the preceding query will be displayed
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| 112 | after each query. This parameter may take the values `yes',
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| 113 | `no', `true', `false', `on' or `off'.
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| 114 |
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| 115 | doc_sepstr = `---------------------------------- %n\n'
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| 116 | This specifies the string that will be used to separate
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| 117 | documents when they are displayed for `boolean' or `docnums'
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| 118 | queries. The standard C escape character sequences (see the
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| 119 | man page) may be used to place special characters in the
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| 120 | string. For example, a newline would the `\n'. To include a `%'
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| 121 | use the sequence `%%'. To include the MG document number use
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| 122 | the sequence `%n'.
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| 123 |
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| 124 | expert = `false'
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| 125 | If this is true then a lot of the waffle that the program
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| 126 | spits out is suppressed. This parameter may take the values
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| 127 | `yes', `no', `true', `false', `on' or `off'.
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| 128 |
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| 129 | hash_tbl_size = `1000'
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| 130 | One of the options during ranking queries is to use a hash
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| 131 | table to accumulate the weights for each document. The hash
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| 132 | table is a simple chained type. This parameter specifies the
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| 133 | size of the hash table and may take any value between 8 and
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| 134 | 268435456.
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| 135 |
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| 136 | heads_length = `50'
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| 137 | When the mode is `heads' this specifies the number of
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| 138 | characters that will be output for each document.
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| 139 |
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| 140 | maxdocs = `all'
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| 141 | The maximum number of documents to display in response to a
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| 142 | query. This parameter may take on a numeric value between 1
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| 143 | and 429467295 or the word `all'.
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| 144 |
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| 145 | maxparas = `1000'
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| 146 | The maximum number of paragraphs to identify during a ranked
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| 147 | query with paragraph indexing. After the paragraphs have been
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| 148 | identified the paragraphs are converted into documents, and
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| 149 | because some of the paragraphs may refer to the same documents
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| 150 | the final number of answers may be less that maxparas. The
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| 151 | maxdocs parameter will then be applied. This parameter may
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| 152 | take on a numeric value between 1 and 429467295.
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| 153 |
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| 154 | max_accumulators = `50000'
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| 155 | This parameter limits the number of different paragraph/
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| 156 | document numbers to be accumulated during ranked queries when
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| 157 | the parameter `accumulator_method` is set to `splay_tree',
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| 158 | `hash_table', or `list'. This parameter may take any value
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| 159 | between 8 and 268435456.
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| 160 |
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| 161 | max_terms = `all'
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| 162 | This parameter limits the number of terms that will actually
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| 163 | be used during a ranked query. If more terms than the number
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| 164 | specified by max_terms are entered, then the extra terms will
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| 165 | be discarded. If `sorted_terms' is on then the limiting will
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| 166 | be done after the terms have been sorted. This parameter may
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| 167 | take any value between 1 and 429467295 or the word `all'.
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| 168 |
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| 169 | memstats = `off'
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| 170 | This is a boolean parameter that determines whether the memory
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| 171 | usage statistics for the preceding query will be displayed
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| 172 | after each query. This parameter may take the values `yes',
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| 173 | `no', `true', `false', `on' or `off'.
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| 174 |
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| 175 | mgdir = `.'
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| 176 | This specifies the directory where the MG files may be found.
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| 177 | If the environment variable `MGDATA' is set then `mgdir' is
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| 178 | initialised to the value in `MGDATA'.
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| 179 |
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| 180 | mgname = `'
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| 181 | This specifies the name of the MG database to process.
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| 182 |
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| 183 | mode = `text'
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| 184 | This specifies how documents should be displayed when they
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| 185 | are retrieved it may take four different values `text',
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| 186 | `docnums', `silent', `heads' or `count'. `text' displays
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| 187 | the contents of the document. `docnums' displays only the
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| 188 | document numbers. `Silent' retrieves all the documents but
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| 189 | displays nothing except how many documents were retrieved.
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| 190 | This mode is intended to be used in timing experiments.
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| 191 | `Heads` is used to print out the head of each document.
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| 192 | `Count' does the minimum amount of work required to determine
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| 193 | how many documents would be retrieved, but does not retrieve
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| 194 | them.
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| 195 |
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| 196 | pager = `more'
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| 197 | This is the name of the program that will be used to display
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| 198 | the help and the retrieved documents. If the environment
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| 199 | variable "PAGER" is defined then `pager' takes on that value.
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| 200 |
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| 201 | para_sepstr = `\n######## PARAGRAPH %n ########\n'
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| 202 | This specifies the string that will be used to separate
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| 203 | paragraphs. The standard C escape character sequences (see the
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| 204 | man page) may be used to place special characters in the
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| 205 | string. For example, a newline would the `\n'. To include a `%'
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| 206 | use the sequence `%%'. To include the paragraph number within
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| 207 | the document use the sequence `%n'.
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| 208 |
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| 209 | para_start = `***** Weight = %w *****\n'
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| 210 | This specifies the string that will be used at the head of
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| 211 | paragraphs for a paraghaph level index following a ranked query.
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| 212 | The standard C escape character sequences (see the man page)
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| 213 | may be used to place special characters in the string. For
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| 214 | example, a newline would the `\n'. To include a `%' use the
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| 215 | sequence `%%'. To include the paragraph weight use the
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| 216 | sequence `%w'.
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| 217 |
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| 218 | qfreq = `true'
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| 219 | This determine whether the ranked queries will take into
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| 220 | account the number of times each query term is specified.
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| 221 | When this is `true' the number of times a term appears in
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| 222 | the query is used in the ranking. When this is `false' all
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| 223 | query term are assumed to occur only once. This parameter
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| 224 | may take the values `yes', `no', `true', `false', `on' or
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| 225 | `off'.
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| 226 |
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| 227 | query = `boolean'
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| 228 | This specifies the type of queries that are to be specified.
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| 229 | It can take four different values `boolean', `ranked',
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| 230 | `docnums' or `approx-ranked'.
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| 231 |
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| 232 | `boolean' is for boolean queries.
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| 233 | The yacc grammar for boolean queries is as follows :-
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| 234 |
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| 235 | query : or;
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| 236 |
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| 237 | or : or '|' and
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| 238 | | and ;
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| 239 |
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| 240 | and : and '&' not
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| 241 | | and not
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| 242 | | not ;
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| 243 |
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| 244 | not : term
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| 245 | | '!' not ;
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| 246 |
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| 247 | term : TERM
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| 248 | | '(' or ')' ;
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| 249 |
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| 250 |
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| 251 |
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| 252 |
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| 253 | `ranked' and `approx-ranked' are for queries ranked by the
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| 254 | cosine measure. `approx-ranked' uses only the low
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| 255 | precision document lengths, and therefore only
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| 256 | produces an approximation to full cosine ranking.
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| 257 |
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| 258 | query : TERM
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| 259 | | query TERM ;
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| 260 |
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| 261 | `docnums' allows the entry of document numbers. Multiple
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| 262 | numbers separated by spaces may be specified
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| 263 | or ranges separated by hyphens.
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| 264 |
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| 265 |
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| 266 | query : range
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| 267 | | query range ;
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| 268 |
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| 269 |
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| 270 | range : num
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| 271 | | num '-' num ;
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| 272 |
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| 273 |
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| 274 | ranked_doc_sepstr = `---------------------------------- %n %w\n'
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| 275 | This specifies the string that will be used to separate
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| 276 | documents when they are displayed for `ranked' or
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| 277 | `approx-ranked' queries. The standard C escape character
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| 278 | sequences (see the man page) may be used to place special
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| 279 | characters in the string. For example, a newline would the
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| 280 | `\n'. To include a `%' use the sequence `%%'. To include the
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| 281 | MG document number use the sequence `%n'. To include the
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| 282 | document weight use the sequence `%w'.
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| 283 |
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| 284 | sizestats = `false'
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| 285 | If this is true then various numbers are output at the end
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| 286 | of each query indicating what went on during the query.
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| 287 | This parameter may take the values `yes', `no', `true',
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| 288 | `false', `on' or `off'.
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| 289 |
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| 290 | skip_dump = `skips.%d'
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| 291 | If this parameter is set then during ranked queries on skipped
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| 292 | inverted files when `accumulator_method' is set to `splay_tree',
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| 293 | `hash_table', or `list` a file will be produced in the current
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| 294 | directory. The name of the file is the value of this parameter,
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| 295 | a `%d' in the file name will be replaced with the process id of
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| 296 | mgquery. This file will contain information about the usage of
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| 297 | skips during the query processing. This option is expensive;
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| 298 | use `.unset skip_dump' to obtain optimal performance.
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| 299 |
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| 300 | sorted_terms = `on'
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| 301 | This specifies whether of not the terms should be sorted into
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| 302 | decreasing occurrence in documents so that the least often
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| 303 | occurring terms are processed first when ranked queries are
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| 304 | being done. When this is true the terms are sorted. When this
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| 305 | is false the terms are not sorted and are instead processed in
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| 306 | order of occurrence. This parameter may take the values `yes',
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| 307 | `no', `true', `false', `on' or `off'.
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| 308 |
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| 309 |
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| 310 | stop_at_max_accum = `on'
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| 311 | This specifies what should happen when the maximum number of
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| 312 | accumulators set by `max_accumulators' is reached. When this
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| 313 | is true the the processing of terms is stopped at the completion
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| 314 | of the current term. When this is false processing continues but
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| 315 | no new accumulators are created. This parameter may take the
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| 316 | values `yes', `no', `true', `false', `on' or `off'.
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| 317 |
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| 318 | terminator = `'
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| 319 | This specifies the string that will be output after the last
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| 320 | document from the previous query has been output. The standard
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| 321 | C escape character sequences (see the man page) may be used to
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| 322 | place special characters in the string. For example, a newline
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| 323 | would the `\n'. To include a `%' use the sequence `%%'.
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| 324 |
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| 325 |
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| 326 | timestats = `false'
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| 327 | If this is true then the time to process a query is displayed
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| 328 | in both real time and CPU time. This parameter may take the
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| 329 | values `yes', `no', `true', `false', `on' or `off'.
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| 330 |
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| 331 | verbatim = `off'
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| 332 | This is a boolean parameter that determines whether the program
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| 333 | should attempt to do a regular expression match on the retrieved
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| 334 | text. If verbatim is `on' and a post-processing strng is specified
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| 335 | with the query then the post-processing string will be searched for
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| 336 | in the documents just before they are displayed. If the string is
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| 337 | found the document will be displayed, if not the document will not
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| 338 | be displayed. If verbatim is `off' the post-processing string will
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| 339 | be considered a regular expression like in `vi' or `egrep'.
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| 340 | E.G. If verbatim is `on', "and.*the" will look for the 8 character
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| 341 | sequence "and.*the". If verbatim is `off', "and.*the" will
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| 342 | look for the sequence "and" followed somewhere later in the
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| 343 | document by the sequence "the".
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| 344 | This parameter may take the values `yes', `no', `true', `false',
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| 345 | `on' or `off'.
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| 346 |
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| 347 |
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