This section is an introduction to the LISTSERV archive search functions, and it is intended to be a reference document for general users with little or no knowledge of database search systems. It does not contain any technical information that general users would have to worry about.
This section will discuss the syntax and operational characteristics of the LISTSERV database subsystem. It is assumed that the reader is familiar with his or her email client and familiar with sending commands to a LISTSERV server.
If you just need a "quick start", read the next two sections for basic instructions. If you want a detailed tutorial on how to use the SEARCH command itself, you might want to skim the next two sections, and then start reading Section 1.3
The SEARCH Command.
To search for the term "Digest=" in the EASE-HOME list on HOME.EASE.LSOFT.COM, create a new mail message addressed to LISTSERV@HOME.EASE.LSOFT.COM and in the body (not the subject) of the message, simply type:
Note: LISTSERV includes excerpts from the indexed postings showing the context of the search term(s). We've deleted all but the first 2 in the example above to save space.
Next, use the GETPOST command to order the specific posts you wanted to read. For instance, if you want to read posts numbered 66 and 74 through 76. You would make another new message (or reply to the response from LISTSERV without quoting the text) and type in the body:
LISTSERV would then respond with the desired postings. For the non-VM servers, GETPOST is analogous to the old database command "PRINT". There is no corresponding command for the old database command INDEX, since the response to a SEARCH command includes the index of matching postings.
It is possible to add further parameters to your search in order to narrow it. You can limit a search by date with a "since. . . " predicate. Likewise, you can limit by sender and/or by the subject line with a "where . . ." predicate. For instance:
Search 'Digest=' in LSTOWN-L since 94/01/01Search 'Digest=' in LSTOWN-L where sender contains 'Thomas'
Search * in LSTOWN-L where sender is ERIC@SEARN
Search * in LSTOWN-L since 94/01/01 where subject contains 'Digest'
Note: The minimum abbreviation of this command is "S".)
Note: The mailing list name doesn't have to be in uppercase.
If you want to "narrow" your previous search, i.e. perform additional tests on the documents that have been previously selected, you must omit the IN keyword. In that case, the search will be applied to the previous "hits" and will create a new "hit list".
Another problem is that we might not remember the exact original sentence. This is not very important, since LISTSERV will search each word individually: in the above example, any entry that contained the words "hardware", "problem", "with", "a" and "4381" would have matched the search, even if the words appeared in a different order.
But, what if the original document had "4381-13" in it, instead of "4381"? This is again no problem, as LISTSERV does not require the word to be surrounded by blanks to find a match. Case is also ignored when performing the search operation. That is, "problem" would have found a match on "problems"... and "with" would have found a match on "without" or "withstand"! This may sound like inconsistent behavior, but you should keep in mind that it is always possible to "narrow down" a search operation. However, once a document has been excluded from the list of "hits", it is very difficult to bring it back.
Now what if I want to search for an exact string? For example, I am interested in the string "in C". It is very likely that just any document in the database will contain both a "in" and the letter C. But what I am interested in is things which have been written, or programmed, or implemented, "in C". In that case, it is possible to force LISTSERV to group words together by quoting them, as in:
This method can also be used to insert extra blanks between or before words: leading and trailing blanks are normally removed automatically, but they are preserved inside quoted strings. Please note that quotes must be doubled when specified inside quoted strings, as in:
The search for 'in C' resulted in over fifty hits, because a match was erroneously found against "in clear", "in core", etc. However, I do not want to search for 'in C ' because there might be hits with "in C." or "in C," in the database and I don't want to miss them. If the search respected the capital C, it would no longer find all those irrelevant hits. To do this, enclose your search string in double-quotes instead of single quotes, for example:
Note: Single quotes should not be doubled inside double-quoted strings, and vice-versa. Only quotes of the same type as the string should be doubled.
It is important to understand the difference between the two types of quoting. If you request a search for 'TEXT', you will find a match on "TEXT", "Text", "text" or even "teXt". This is the same behavior as unquoted text. However, if you request a search for "TEXT", it will only find a match on "TEXT", not on "text" or "Text".
Quoting is also the only way to search for a reserved keyword like "IN": if you tried "Search in in UTILITY", LISTSERV would report that database "IN" does not exist and would reject the command. This is because the keyword IN indicates the end of your search arguments. If you quote it, however, it will not be recognized and will be searched as you wanted it done. Similarly, if you want to search for an asterisk, you will have to quote it since
Now the problem is that there may be sentences starting with a capital I, e.g. "In C, it would be coded this way:". How can I catch these sentences? Actually, you have been using "complex search expressions" from the beginning without even being aware of it. When you specified a search on
Note: This is a change from the way the "locate" clause was implemented in 1.8b and earlier. Earlier versions used a default of "AND" instead of "NEAR" between discrete search terms. The difference is that
Since each document has been assigned a "date/time" field, it is possible to select documents based on this date field. This is accomplished by appending "date search rules" to the search expression, as in:
The default values for omitted arguments are always chosen so as to exclude as few entries as possible. For example, "July" would mean "1 July 00:00:00" in a SINCE specification, and "31 July 23:59:59" in an UNTIL clause. The only exception is the year field, which always defaults to the current year.
The last thing you may wish to search is the "keywords" list. For example, you might want to select those plastic chairs which cost less than 50 dollars. It is assumed that the price will vary often (maybe almost daily), and that it is therefore kept externally from the document describing the chair. Thus, you would have a "Price" keyword which you could search in the following way:
You may of course use complex expressions (with parenthesis) in the WHERE clause. There are new comparison operators available for this clause, like IS, CONTAINS, all the usual arithmetical comparison operators, and some more. However, the AND operation is no longer implied, but it can still be specified explicitly of course:
The problem now is that, as the search commands become more and more complex, they will no longer fit in a single line. To solve this problem, we begin the command with the string "// " (two front-slashes and a space) and follow it with the SEARCH command and the search specifications. Any database command ending in a comma indicates that more is to follow on the next line. This process can be repeated several times if desired.
The only "trick" about this continuation line business is that you should always keep quoted strings on a single line. The process of identifying continuation lines and concatenating them afterwards may cause unwanted blanks to be inserted in the command line, which is no problem outside a quoted string since blanks are ignored, but might cause erroneous results in a quoted string.
However, it should be noted that this "factorization" is performed according to the rules of logic, which may not necessarily match those of English grammar. This removes any possible ambiguity as to the meaning of these clauses. Let's consider the following:
In English, you would probably say "machine contains neither IBM nor DEC". This is how LISTSERV will understand it. However, if you read the clause aloud, you will probably not pronounce the parenthesis and will end up saying "machine does not contain IBM and DEC"; in other words, "machine does not contain both IBM and DEC", which is a totally different thing. The "English meaning" could be obtained with the following clause:
In the former case, the negative "does not contain" operator is inserted inside the parenthesis. In the latter, only "contains" is moved, and the negation remains outside.
There may be cases where you are looking for a certain value of a keyword, the exact spelling of which you cannot remember. In these cases, it may be useful to try a phonetic search. A phonetic search will yield a match for anything that "sounds like" your search string, as dictated by a predefined algorithm which is of course not perfect. It may give a hit for something which does not actually sound like your search string, or, more rarely, omit a keyword which did sound like what you entered. The main reasons for this are that the algorithm must be fast to execute on the machine and therefore not too sophisticated, and that the way a given word is pronounced depends on the idiom in which the word was written. For example, the phonetical transcription of the name "Landau" will be different in French, English, German and Russian. Thus, it is impossible to decide whether a word sounds like another if the language in which the words are pronounced is not known (and of course LISTSERV does not have any way to know it).
Phonetic searches are performed through the use of the SOUNDS LIKE and DOES NOT SOUND LIKE operators, which are syntactically similar to CONTAINS and DOES NOT CONTAIN. That is, you could do something like:
There is a little trick with the SOUNDS LIKE operator that you should be aware of. If your search string (WOLF in our above example) is a single word, it will be compared individually to all the words in the reference string (i.e. the data from the database), and will be considered a hit if it "sounds like" any of the words in the reference string. Thus, the search word "Ekohl" sounds like the reference string "Ecole Normale Superieure" because it matches the first word. If the search string contains more than one word, the search and reference strings will be compared phonetically as a whole (and "Ekohl Dzentrahll" will therefore not match "Ecole Normale Superieure"). Note that any search string containing more than a single word must be quoted, as explained in the previous sections.
Above, the first command shows an example of accurate phonetic match, where the result is exactly what the user expected. In the second example, the user found what he was looking for ("Optics"), but an additional unwanted entry was selected. This is by far the most common case. The last command is a typical example of phonetic clash, where the algorithm did not translate the search string into phonetics as the user expected it, with the result that the desired name ("Chicago") was not found and that completely irrelevant entries were presented instead.
The phonetic matching algorithm used by LISTSERV is a slightly modified version of SOUNDEX -- a well-known algorithm that provides reasonably accurate matches at a very low CPU cost. Although it gives best results with the English language, for which it was originally designed, it is not too strongly tied to it and can still be used with other languages. It is of course absolutely impossible to write an program that would work for all the languages in the world, or even for the most widely used ones, since their interpretation of the most common combinations of letters are completely incompatible.
LISTSERV limits the number of matching records in a given response to no more than 100. This is done primarily to stop hackers from tying up the server with SEARCH requests on lists with thousands of archived postings, but it also keeps the size of the response down to a manageable level. For instance, sending a "SEARCH *" command for an old, very large list could result in a response measuring in megabytes if not for the 100-record limitation.
Starting with LISTSERV 1.8d it is possible to specify that your search criteria be applied to only the last n posts in the archive. For instance, say you are only interested in checking the last 50 postings of LSTOWN-L to see if nathan@lsoft.com posted. You would send
Again you would have to use the hyphen after the number. The number n can be any integer, but as with any other search, if LISTSERV finds more than 100 hits only the first 100 will be returned to you. Thus it would be possible for n to be 1000, or even 10,000, but you will still have to narrow your search if you want more hits.
Month names can be abbreviated to any length. If there is an ambiguity, the first month in chronological order is retained. For example, "J" would mean "January", "JU" would be "June" and "JUL" would unambiguously select "July".
Note: Case is irrelevant in date specifications. The keywords (SINCE, UNTIL, etc.) have been capitalized only for better legibility and be entered in lower case, if desired.
"kwd-expression" is, generally speaking, an mathematical expression of keyword/value comparisons, possibly bound by logical operators. Comparison operators have a higher precedence than logical operators, that is, "A>10 AND B=20" is interpreted as "(A>10) AND (B=20)". The available comparison operators are listed below. All the operators appearing on a given line are synonyms.
All these operators are self-explanatory, except the last two which allow you to search the keyword value for a given "substring". That is, "Sender contains jeff" would be true if the value of the "Sender" keyword was "Jeff Smith" or "Jeffrey Donaldson". The case is ignored during the comparison unless the search operand is double-quoted.
Note: The logical operators AND and OR have equal precedence and are evaluated left to right.
Finally, you must specify what is to be searched inside the document. If you do not want anything to be sought at all (e.g. if you are only selecting known items from the database), you can specify an asterisk as a placeholder to waive the search. Otherwise you must specify a mathematical expression where arguments are search strings, possibly bound by logical operators (see Figure 10 for a comprehensive list). The default operator is AND, so that a search for "INTERPRET STEM PROBLEM" will select all entries where "INTERPRET", "STEM" and "PROBLEM" can be found (not necessarily in the same line).
Strings quoted in single-quotes (') are converted to upper case and cause case to be ignored during the search. That is, they behave in the same manner as un-quoted strings as far as the search algorithm is concerned. As a rule of thumb, any string can be single-quoted if desired, even if it does not have to.
Strings quoted in double-quotes (") are not converted to upper case. They result in a case-sensitive search, which means that you should never double-quote a string unless you want case to be respected during the search.
