Provided by:
debathena-discuss_10.0.12-0debathena3~ubuntu10.04_i386 
NAME
dsgrep - Search discuss meetings with regular expressions
SYNOPSIS
dsgrep [-n n_trans] [-e search_regexp] [-f meetings_file] [-t
trans_num] [-a] [-p] [-v] [-i] [meetingname1 meetingname2 ...]
DESCRIPTION
Dsgrep searches discuss meetings for transactions that have titles that
match the given regular expression, or have contents that match the
regular expression. The title of the matching transactions or their
contents can be printed.
Dsgrep understands the following options:
-n n_trans specifies the number of transactions to look back from the
last transaction in each discuss meeting specified. This
defaults to 50. This option is ignored when the -t option
is specified.
-e search_regexp
This specifies the regular expression to be matched, in the
style of egrep(1). A detailed explaination of the regular
expression format is given below. If this is omitted, it
defaults to "*", matching all transactions.
-f meetings_file
This specifies an alternative meetings file to use as a
source of meetings. If this option is not specified, it
will use the file ${HOME}/.meetings.,
-t trans_num
Print out a specific transaction, by number. When this
option is used, the -n option is ignored.
-a Causes dsgrep to search the text of the transactions for
the regular expressions as well as their titles.
-p Causes the text of the text of the matching transactions to
be printed instead of just the title.
-v Causes errors getting transactions to be reported. These
errors are usually due to deleted transactions in the
meetings, and are ususally not worth seeing.
-d Causes deleted transactions to be searched as well.
Otherwise, deleted transactions are ignored.
-i Ignores case when matching against search_regexp.
meetings This specifies the meetings to search; if it is left off,
dsgrep will search all the meetings.
REGULAR EXPRESSION SYNTAX
A regular expression is zero or more branches, separated by `|'. It
matches anything that matches one of the branches.
A branch is zero or more pieces, concatenated. It matches a match for
the first, followed by a match for the second, etc.
A piece is an atom possibly followed by `*', `+', or `?'. An atom
followed by `*' matches a sequence of 0 or more matches of the atom.
An atom followed by `+' matches a sequence of 1 or more matches of the
atom. An atom followed by `?' matches a match of the atom, or the null
string.
An atom is a regular expression in parentheses (matching a match for
the regular expression), a range (see below), `.' (matching any single
character), `^' (matching the null string at the beginning of the input
string), `$' (matching the null string at the end of the input string),
a `\' followed by a single character (matching that character), or a
single character with no other significance (matching that character).
A range is a sequence of characters enclosed in `[]'. It normally
matches any single character from the sequence. If the sequence begins
with `^', it matches any single character not from the rest of the
sequence. If two characters in the sequence are separated by `-', this
is shorthand for the full list of ASCII characters between them (e.g.
`[0-9]' matches any decimal digit). To include a literal `]' in the
sequence, make it the first character (following a possible `^'). To
include a literal `-', make it the first or last character.
AMBIGUITY
If a regular expression could match two different parts of the input
string, it will match the one which begins earliest. If both begin in
the same place but match different lengths, or match the same length
in different ways, life gets messier, as follows.
In general, the possibilities in a list of branches are considered in
left-to-right order, the possibilities for `*', `+', and `?' are
considered longest-first, nested constructs are considered from the
outermost in, and concatenated constructs are considered leftmost-
first. The match that will be chosen is the one that uses the earliest
possibility in the first choice that has to be made. If there is more
than one choice, the next will be made in the same manner (earliest
possibility) subject to the decision on the first choice. And so
forth.
For example, `(ab|a)b*c' could match `abc' in one of two ways. The
first choice is between `ab' and `a'; since `ab' is earlier, and does
lead to a successful overall match, it is chosen. Since the `b' is
already spoken for, the `b*' must match its last possibility—the empty
string—since it must respect the earlier choice.
In the particular case where no `|'s are present and there is only one
`*', `+', or `?', the net effect is that the longest possible match
will be chosen. So `ab*', presented with `xabbbby', will match
`abbbb'. Note that if `ab*' is tried against `xabyabbbz', it will
match `ab' just after `x', due to the begins-earliest rule. (In
effect, the decision on where to start the match is the first choice to
be made, hence subsequent choices must respect it even if this leads
them to less-preferred alternatives.)
SEE ALSO
egrep(1), discuss(1)
18 Jun 1990 DSGREP(1)