glimpse.1

harvest是一个下载html网页得机器人

.TP
.B \-L x | x:y | x:y:z
if one number is given, it is a limit on the total number of matches.
Glimpse outputs only the first x matches.  
If \-l is used (i.e., only file names
are sought), then the limit is on the number of files;
otherwise, the limit is on the number of records.
If two numbers are given (x:y), then y is an added limit on the total
number of files.
If three numbers are given (x:y:z), then z is an added limit on the
number of matches per file.
If any of the x, y, or z is set to 0, it means to ignore it
(in other words 0 = infinity in this case);  for example,
\-L 0:10 will output all matches to the first 10 files that
contain a match.
This option is particularly
useful for servers that needs to limit the amount of
output provided to clients.
.TP
.B \-m
used for glimpse internals.
.TP
.B \-M
used for glimpse internals.
.TP
.B \-n
Each matching record (line) is prefixed by its record (line) number in the file.
\fBPerformance Note:\fP
To compute the record/line number, agrep needs to search for all
record delimiters (or line breaks), which can slow down the search.
.TP
.B \-N
searches only the index (so the search is faster).
If -o or -b are used then the result is the number of files
that have a potential match plus a prompt to ask if you want to
see the file names.
(If \-y is used, then there is no prompt and the names of the
files will be shown.)
This could be a way to get the matching file names without even having
access to the files themselves.
However, because only the index is searched, some potential matches
may not be real matches.
In other words, with \-N you will not miss any file but you may get
extra files.
For example, since the index stores everything in lower case,
a case-sensitive query may match a file that has only a case-insensitive
match.  Boolean queries may match a file that has all the keywords
but not in the same line (indexing with \-b allows glimpse to
figure out whether the keywords are close, but it cannot figure out
from the index whether they are exactly on the same line or in the same record
without looking at the file).
If the index was not build with \-o or \-b, then this option 
outputs the number of \fIblocks\fP matching the pattern.  
This is useful as an indication of how long the search will take.
All files are partitioned into usually 200-250 blocks.
The file \fB.glimpse_statistics\fP contains the total number of blocks
(or \fBglimpse -N a\fP will give a pretty good estimate; only blocks with no
occurrences of 'a' will be missed).
.TP
.B \-o
the opposite of \-t: the delimiter
is not output at the tail, but at the beginning of the matched record.
.TP
.B \-O
the file names are not printed before every matched record;
instead, each filename is printed just once,
and all the matched records within it are printed after it.
.TP
.B \-p
(from version 4.0B1 only) Supports reading compressed
set of filenames.
The -p option allows you to utilize compressed `neighborhoods'
(sets of filenames) to limit your search, without uncompressing them.
Added mostly for WebGlimpse.
The usage is:
.br
"-p filename:X:Y:Z"
where "filename" is the file with compressed neighborhoods, X is an
offset into that file (usually 0, must be a multiple of sizeof(int)),
Y is the length glimpse must access from that file (if 0, then whole file;
must be a multiple of sizeof(int)), and Z must be 2 (it indicates
that "filename" has the sparse-set representation of compressed
neighborhoods: the other values are for internal use only). Note that
any colon ":" in filename must be escaped using a backslash \.
.TP
.B \-P
used for glimpse internals.
.TP
.B \-q
prints the offsets of the beginning and end of each matched record.
The difference between \-q and \-b is that \-b prints the offsets
of the actual matched string, while \-q prints the offsets of the
whole record where the match occurred. 
The output format is @x{y}, where x is the beginning offset
and y is the end offset.
.TP
.B \-Q
when used together with \-N glimpse not only displays the filename where
the match occurs, but the exact occurrences (offsets) as seen in the
index.  This option is relevant only if the index was built
with -b;  otherwise, the offsets are not available in the index.
This option is ignored when used not with \-N.
.TP
.B \-r
This option is an agrep option and it will be ignored in glimpse,
unless glimpse is used with a file name at the end which makes it
run as agrep.
If the file name is a directory name, the \-r option will search
(recursively) the whole directory and everything below it.
(The glimpse index will not be used.)
.TP
.B \-R \fIk\fP
defines the maximum size (in bytes) of a record.
The maximum value (which is the default) is 48K.
Defining the maximum to be lower than the deafult may speed
up some searches.
.TP
.B \-s   
Work silently, that is, display nothing except error messages.
This is useful for checking the error status.
.TP
.B \-S\fIk\fP
Set the cost of a substitution to \fIk\fP (\fIk\fP is a positive integer).
This option does not currently work with regular expressions.
.TP
.B \-t   
Similar to the \-d option, except that the delimiter is assumed
to appear at the \fIend\fP of the record.
Glimpse will output the record starting from the end of 
.I delim
to (and including) the next
.I delim.
(See warning for the \-d option.)
.TP
.B \-T directory 
Use \fIdirectory\fP as a place where temporary files are built.
(Glimpse produces some small temporary files usually in /tmp.)
This option is useful mainly in the context of structured queries
for the Harvest project, where the temporary files may be non-trivial,
and the /tmp directory may not have enough space for them.
.TP
.B \-U
(starting at version 4.0B1) Interprets an index created
with the -X or the -U option in glimpseindex. 
Useful mostly for WebGlimpse or similar web applications.
When glimpse outputs matches, it
will display the filename, the URL, and the title automatically.
.TP
.B \-v
(This option is an agrep option and it will be ignored in glimpse,
unless glimpse is used with a file name at the end which makes it
run as agrep.)
Output all records/lines that do \fInot\fP contain a match.
(Glimpse does not support the NOT operator yet.)
.TP
.B \-V
prints the current version of glimpse.
.TP
.B \-w
Search for the pattern as a word \(em i.e., surrounded by non-alphanumeric
characters.  For example, 
\fIglimpse -w car\fR will match car, but not characters and not
car10.
The non-alphanumeric \fImust\fP
surround the match;  they cannot be counted as errors.
This option does not work with regular expressions.
\fBPerformance Note:\fP
When \-w is used together with the \-i option, 
the search may become much faster.
The \-w will not work with $, ^, and _ (see BUGS below).
It is recommended to have \-i and \-w as defaults, for example,
through an alias.  We use the following alias in our .cshrc file
.br
alias glwi 'glimpse -w -i'
.TP
.B \-W
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 containing
both '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' 
\fIor\fP 'bad', but only in files that contain both patterns.
The NOT operator '~' can be used only with \-W.
It is described later on.
The OR operator is essentially unaffected (unless it is
in combination with the other Boolean operations).
For structured queries, the scope is always the whole attribute
or file.
.TP
.B \-x
The pattern must match the whole line.
(This option is translated to -w when the index is searched
and it is used only when the actual text is searched.
It is of limited use in glimpse.)
.TP
.B \-X
(from version 4.0B1 only) Output the names of files that
contain a match even if these files have been deleted since the
index was built.
Without this option glimpse will simply ignore these files.
.TP
.B \-y
Do not prompt.
Proceed with the match as if the answer to any prompt is y.
Servers (or any other scripts) using glimpse will probably want
to use this option.
.TP
.B \-Y \fIk\fP
If the index was constructed with the -t option, then \-Y x
will output only matches to files that were created or
modified within the last x days.
There are no major performance penalties for this option.
.TP
.B \-z
Allow customizable filtering, using the file .glimpse_filters 
to perform the programs listed there for each match.  
The best example is
compress/decompress.  If .glimpse_filters include the line
.br
*.Z   uncompress <
.br
(separated by tabs)
then before indexing any file that matches the pattern "*.Z" (same
syntax as the one for .glimpse_exclude) the command listed is
executed first (assuming input is from stdin, which is why uncompress
needs <) and its output (assuming it goes to stdout) is indexed.
The file itself is not changed (i.e., it stays compressed).
Then if glimpse -z is used, the same program is used on these files
on the fly.  Any program can be used (we run 'exec').  For example,
one can filter out parts of files that should not be indexed.
Glimpseindex tries to apply all filters in .glimpse_filters in the
order they are given.
For example, if you want to uncompress a file and then extract
some part of it, put the compression command (the example above)
first and then another line that specifies the extraction.
Note that this can slow down the search because the filters need to
be run before files are searched.
(See also glimpseindex.)
.TP
.B \-Z
No op.  (It's useful for glimpse's internals. Trust us.)
.LP
The characters
.RB ` $ ',
.RB `^ ',
.RB ` \(** ',
.RB ` [ ' ,
.RB ` ] ' ,
.RB ` \s+2^\s0 ',
.RB ` | ',
.RB ` ( ',
.RB ` ) ',
.RB ` ! ',
and
.RB ` \e '
can cause unexpected results when included in the
.IR pattern ,
as these characters are also meaningful
to the shell.  To avoid these problems, enclose the entire
pattern in single quotes, i.e., 'pattern'.
Do not use double quotes (").
.ne 4
.SH PATTERNS
.LP
\fIglimpse\fP 
supports a large variety of patterns, including simple
strings, strings with classes of characters, sets of strings, 
wild cards, and regular expressions (see LIMITATIONS).
.TP
\fBStrings   \fP
Strings are any sequence of characters, including the special symbols
`^' for beginning of line and `$' for end of line.
The following special characters (
.RB ` $ ',
.RB `^ ',
.RB ` \(** ',
.RB ` [ ' ,
.RB ` \s+2^\s0 ',
.RB ` | ',
.RB ` ( ',
.RB ` ) ',
.RB ` ! ',
and
.RB ` \e '
) 
as well as the following meta characters special to glimpse (and agrep):
.RB ` ; ',
.RB ` , ',
.RB ` # ',
.RB ` < ',
.RB ` > ',
.RB ` - ',
and
.RB ` . ',
should be preceded by `\\' if they are to be matched as regular
characters.  For example, \\^abc\\\\ corresponds to the string ^abc\\,
whereas ^abc corresponds to the string abc at the beginning of a
line.
.TP
\fBClasses of characters\fP
a list of characters inside [] (in order) corresponds to any character
from the list.  For example, [a-ho-z] is any character between a and h
or between o and z.  The symbol `^' inside [] complements the list.
For example, [^i-n] denote any character in the character set except
character 'i' to 'n'.
The symbol `^' thus has two meanings, but this is consistent with
egrep.
The symbol `.' (don't care) stands for any symbol (except for the
newline symbol).
.TP
\fBBoolean operations\fP
.B Glimpse 
supports an `AND' operation denoted by the symbol `;' 
an `OR' operation denoted by the symbol `,',
a limited version of a 'NOT' operation (starting at version 4.0B1)
denoted by the symbol `~',
or any combination.  
For example,
\fIglimpse 'pizza;cheeseburger'\fR will output all lines containing