Patterns are used in triggers, hooks, /purge, /list, and /recall. There are three styles of pattern matching available: "simple" comparison, "glob" (similar to shell filename patterns), and "regexp" (regular expressions). The style used by a particular command is determined either by the use of the -m option or the setting of the global variable %{matching}.
The pattern is compared directly to the string. There are no special characters. Case is significant.
Globbing is the default matching style, and was the only style available before version 3.2. It is similar to filename expansion ("globbing") used by many shells (but is only used for comparison, not expansion).
There are several special sequences that can be used in tf globbing:
Patterns containing "{...}" can easily be meaningless. A valid {...} pattern must: (a) contain no spaces, (b) follow a wildcard, space, or beginning of string, (c) be followed by a wildcard, space, or end of string.
The pattern "{}" will match the empty string.
Examples:
"d?g" matches "dog", "dig" and "dug" but not "dg" or "drug".
"d*g" matches "dg", "dog", "drug", "debug", "dead slug", etc.
"{d*g}" matches "dg", "dog", "drug", "debug", but not "dead slug".
"M[rs]." matches "Mr." and "Ms."
"M[a-z]" matches "Ma", "Mb", "Mc", etc.
"[^a-z]" matches any character that is not in the English alphabet.
"{storm|chup*}*" matches "chupchup fehs" and "Storm jiggles".
"{storm|chup*}*" does NOT match "stormette jiggles".
The regexp package was written by Henry Spencer, and is similar to those used in egrep and many text editors. See also: regmatch(), substitution. The following excerpt is taken from Henry Spencer's regexp(3) man page.
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.)
regexp equivalent glob
(except for case)
------ -----------------
"part of line" "*part of line*"
"^entire line$" "entire line"
"(^| )word( |$)" "*{word}*"
"^(You|Hawkeye) " "{You|Hawkeye} *"
"foo.*bar" "*foo*bar*"
"f(oo|00)d" "*{*food*|*f00d*}*"
"line[0-9]" "*line[0-9]*"
"^[^ ]+ whispers," "{*} whispers,*"
"foo(AB)?bar" "*{*foobar*|*fooABbar*}*"
"zoo+m" none
"foo ?bar" none
"(foo bar|frodo)" none
.*" or "^.*" at the beginning of a
regexp. It is very inefficient, and not needed. Use
%PL instead if you need to
retrieve the value of the left side.