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Content-type: text/html<HTML><HEAD><TITLE>Manual Pages - Search Help</TITLE><!-- Changed by: Michael Hamilton, 6-Apr-1996 --><!-- Note: this is not html, but requires preprocessing --></HEAD><BODY><H1>Manual Pages - Search Help</H1><A HREF="%cg/mansearch">Perform another search</A><BR><A HREF="%cg/man2html">Return to Main Contents</A><P><HR><P>The full text index uses the <I>Glimpse</I> text indexing system.The <A HREF="%cg/man2html?1+glimpse">glimpse(1)</A>manual page documents glimpse in full. This summary documents thosefeatures of glimpse that are valid when searching through the manual pages.<P><HR><H2>Search Options</H2>The following search options must be at the start of the search string.<DL COMPACT><DT><B>-</B> <I>#</I><DD><I>#</I> is an integer between 1 and 8specifying the maximum number of errorspermitted in finding the approximate matches (the default is zero).Generally, each insertion, deletion, or substitution counts as one error.Since the index stores only lower case characters, errors ofsubstituting upper case with lower case may be missed.<DT><B>-B</B><DD>Best match mode. (Warning: -B sometimes misses matches. It is saferto specify the number of errors explicitly.)When -B is specified and no exact matches are found, glimpsewill continue to search until the closest matches (i.e., the oneswith minimum number of errors)are found.In general, -B may be slower than -#, but not by very much.Since the index stores only lower case characters, errors ofsubstituting upper case with lower case may be missed.<DT><B>-L <I>x</I> | <I>x</I>:<I>y</I> | <I>x</I>:<I>y</I>:<I>z</I></B><DD>A non-zero value of <I>x</I> limits the number of matchesthat will be shown. A non-zero value of <I>y</I> limits the number of man pagesthat will be shown.A non-zero valye of <I>z</I> will only show pages that haveless that z matches.For example, -L 0:10 will output all matches for the first 10 files thatcontain a match.<DT><B>-F</B> <I>pattern</I><DD>The -F option provides a pattern that restricts the search results tothose filenames that match the pattern.or example, <I>-F 8</I> effectively restricts matches to section 8.<DT><B>-w</B><DD>Search for the pattern as a word - i.e., surrounded by non-alphanumericcharacters. For example, <I>-w -1 car</I> will match cars, but not characters and notcar10.The non-alphanumeric <I>must</I>surround the match; they cannot be counted as errors.This option does not work with regular expressions.<DT><B>-W</B><DD>The default for Boolean AND queries is that they cover one record(the default for a record is one line) at a time. For example, glimpse 'good;bad' will output all lines containingboth 'good' and 'bad'.The -W option changes the scope of Booleans to be the whole file.Within a file glimpse will output all matches to any of the patterns.So, glimpse -W 'good;bad' will output all lines containing 'good' <I>or</I> 'bad', but only in files that contain both patterns.<DT><B>-k</B><DD>No symbol in the pattern is treated as a meta character. For example, <I>-k a(b|c)*d</I> will find the occurrences of a(b|c)*d whereas <I>a(b|c)*d</I>will find substrings that match the regular expression 'a(b|c)*d'.(The only exception is ^ at the beginning of the pattern and $ at theend of the pattern, which are still interpreted in the usual way. Use \^ or \$ if you need them verbatim.)</DL><P><HR><H2>Patterns</H2><I>Glimpse</I> supports a large variety of patterns, including simplestrings, strings with classes of characters, sets of strings, wild cards, and regular expressions (see <A HREF="#limitations">LIMITATIONS</A>).<DL COMPACT><DT><B>Strings </B><DD>Strings are any sequence of characters, including the special symbols`^' for beginning of line and `$' for end of line.The following special characters (`<B>$</B>',`^<B>',</B>`<B>*</B>',`<B>[</B>'<B>,</B>`<B>^</B>',`<B>|</B>',`<B>(</B>',`<B>)</B>',`<B>!</B>',and`<B>\</B>') as well as the following meta characters special to glimpse (and agrep):`<B>;</B>',`<B>,</B>',`<B>#</B>',`<B><</B>',`<B>></B>',`<B>-</B>',and`<B>.</B>',should be preceded by `\' if they are to be matched as regularcharacters. For example, \^abc\\ corresponds to the string ^abc\,whereas ^abc corresponds to the string abc at the beginning of aline.<DT><B>Classes of characters</B><DD>a list of characters inside [] (in order) corresponds to any characterfrom the list. For example, [a-ho-z] is any character between a and hor between o and z. The symbol `^' inside [] complements the list.For example, [^i-n] denote any character in the character set exceptcharacter 'i' to 'n'.The symbol `^' thus has two meanings, but this is consistent withegrep.The symbol `.' (don't care) stands for any symbol (except for thenewline symbol).<DT><B>Boolean operations</B><DD><B>Glimpse </B>supports an `AND' operation denoted by the symbol `;' an `OR' operation denoted by the symbol `,',or any combination. For example,<I>glimpse 'pizza;cheeseburger'</I> will output all lines containingboth patterns.<I>glimpse -F 'gnu;\.c$' 'define;DEFAULT'</I>will output all lines containing both 'define' and 'DEFAULT'(anywhere in the line, not necessarily in order) infiles whose name contains 'gnu' and ends with .c.<I>glimpse '{political,computer};science'</I> will match 'political science' or 'science of computers'.<DT><B>Wild cards</B><DD>The symbol '#' is used to denote a sequence of any number (including 0) of arbitrary characters (see <A HREF="#limitations">LIMITATIONS</A>). The symbol # is equivalent to .* in egrep.In fact, .* will work too, because it is a valid regular expression(see below), but unless this is part of an actual regular expression,# will work faster. (Currently glimpse is experiencing some problems with #.)<DT><B>Combination of exact and approximate matching</B><DD>Any pattern inside angle brackets <> must match the text exactly evenif the match is with errors. For example, <mathemat>ics matchesmathematical with one error (replacing the last s with an a), butmathe<matics> does not match mathematical no matter how many errors areallowed.(This option is buggy at the moment.)<DT><B>Regular expressions</B><DD>Since the index is word based, a regular expression must matchwords that appear in the index for glimpse to find it.Glimpse first strips the regular expression from all non-alphabeticcharacters, and searches the index for all remaining words.It then applies the regular expression matching algorithm to thefiles found in the index.For example, <I>glimpse</I> 'abc.*xyz' will search the indexfor all files that contain both 'abc' and 'xyz', and thensearch directly for 'abc.*xyz' in those files.(If you use glimpse -w 'abc.*xyz', then 'abcxyz' will not be found, because glimpsewill think that abc and xyz need to be matches to whole words.)The syntax of regular expressions in <B>glimpse</B> is in general the same asthat for <B>agrep</B>. The union operation `|', Kleene closure `*',and parentheses () are all supported.Currently '+' is not supported.Regular expressions are currently limited to approximately 30characters (generally excluding meta characters). Some options(-d, -w, -t, -x, -D, -I, -S) do not currently work with regular expressions.The maximal number of errors for regular expressions that use '*'or '|' is 4. (See <A HREF="#limitations">LIMITATIONS</A>.)</DL><HR><H2><A NAME="limitations">Limitations</A></H2>The index of glimpse is word based. A pattern that contains more thanone word cannot be found in the index. The way glimpse overcomes thisweakness is by splitting any multi-word pattern into its set of wordsand looking for all of them in the index.For example, <B>glimpse 'linear programming'</B> will first consult the indexto find all files containing both <I>linear</I> and <I>programming</I>,and then apply agrep to find the combined pattern.This is usually an effective solution, but it can be slow forcases where both words are very common, but their combination is not.<P>As was mentioned in the section on PATTERNS above, some charactersserve as meta characters for glimpse and need to bepreceded by '\' to search for them. The most commonexamples are the characters '.' (which stands for a wild card),and '*' (the Kleene closure).So, "glimpse ab.de" will match abcde, but "glimpse ab\.de"will not, and "glimpse ab*de" will not match ab*de, but "glimpse ab\*de" will.The meta character - is translated automatically to a hyphenunless it appears between [] (in which case it denotes a range ofcharacters).<P>The index of glimpse stores all patterns in lower case.When glimpse searches the index it first convertsall patterns to lower case, finds the appropriate files,and then searches the actual files using the originalpatterns.So, for example, <I>glimpse ABCXYZ</I> will first find allfiles containing abcxyz in any combination of lower and uppercases, and then searches these files directly, so only theright cases will be found.One problem with this approach is discovering misspellingsthat are caused by wrong cases.For example, <I>glimpse -B abcXYZ</I> will first search theindex for the best match to abcxyz (because the pattern isconverted to lower case); it will find that there are matcheswith no errors, and will go to those files to search themdirectly, this time with the original upper cases. If the closest match is, say AbcXYZ, glimpse may miss it,because it doesn't expect an error.Another problem is speed. If you search for "ATT", it will lookat the index for "att". Unless you use -w to match the whole word,glimpse may have to search all files containing, for example, "Seattle"which has "att" in it.<P>There is no size limit for simple patterns and simple patternswithin Boolean expressions.More complicated patterns, such as regular expressions,are currently limited to approximately 30 characters.Lines are limited to 1024 characters.Records are limited to 48K, and may be truncated if they are largerthan that.The limit of record length can be changed by modifying the parameter Max_record in agrep.h.<P>Glimpseindex does not index words of size > 64.<A NAME="lbAQ"> </A><HR></BODY></HTML>⌨️ 快捷键说明
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