OmniGraffle's Find dialog supports the use of some simple regular expressions. A regular expression is a single string that represents a whole set of strings. The following syntax is used: a* — zero or more instances of a (matches the longest string possible)
a*? — zero or more instances of a (matches the shortest string possible)
a+ — one or more instances of a (matches the longest string possible)
a+? — one or more instances of a (matches the shortest string possible)
a? — zero or one instance of a
^ — beginning of a line
$ — end of a line
. — any character
[a-z] — all characters between a and z
[abc-] — a, b, c, or -
(abc) — matches abc and stores it as a group. Use the Select or Replace pop-up menu in the Find dialog to select or replace only one of these groups rather than the whole expression.
\1 — text of first matched group
a|b — a or b
\n — newline
\r — carriage return
\t — tab character
\d — digit
\D — non-digit
\w — word character (alphanumeric or underscore)
\W — non-word character
\s — whitespace
\S — non-whitespace
\ — escape the next character
Regular expressions are very popular, so you should be able to find plenty of information about them on the internet or in a good library or bookstore. Here are a few examples to get you started: \s*$ — matches whitespace at the end of a line.
<.*?> — matches strings that begin with < and end with >, such as XML tags.
\S+@\S+ — very liberally matches things that resemble e-mail addresses (anything@anything).
(19|20)\d\d-\d\d?-\d\d? — matches dates in the format YYYY-MM-DD, between 1900 and 2099