Extracted from the Glimpse Man Page

The font size is increased here so you can read the commas, quotes, and
semi colins.

**Boolean operations**

**Glimpse** (the search engine) supports an `AND' operation denoted
by the symbol `;' an `OR' operation denoted by the
symbol `,', or any combination. For example, `*pizza*;*cheeseburger*' will output all
lines containing both patterns. *define*;*DEFAULT*'
will output all lines containing both `define' and
`DEFAULT' (anywhere in the line, not necessarily in
order). `{*political*,*computer*};*science*'
will match `political science' or `science of computers'.

**Wild cards**

The symbol `#' is used to denote a sequence of any
number (including 0) of arbitrary characters.
The symbol # is equivalent to .* in egrep. In fact,
.* will work too, because it is a valid regular expression
(see below), but unless this is part of an actual regular
expression, # will work faster. (Currently glimpse
is experiencing some problems with #.)

**Combination of exact and approximate matching**
Any pattern inside angle brackets <> must match
the text exactly even if the match is with errors.
For example, <mathemat>ics matches mathematical
with one error (replacing the last s with an a), but
mathe<matics> does not match mathematical no
matter how many errors are allowed. (This option is
buggy at the moment.)

**Regular expressions**

Since the index is word based, a regular expression
must match words that appear in the index for glimpse
to find it. Glimpse first strips the regular expression
from all non-alphabetic characters, and searches the
index for all remaining words. It then applies the
regular expression matching algorithm to the files
found in the index. For example, `abc.*xyz'
will search the index for all files that contain both
`abc' and `xyz', and then search directly for `abc.*xyz'
in those files. The syntax of regular expressions in **glimpse**
is in general the same as that for **agrep**. The
union operation `|', Kleene closure `*', and parentheses
() are all supported. Currently `+' is not supported.
Regular expressions are currently limited to approximately
30 characters (generally excluding meta characters). The maximal number of
errors for regular expressions that use `*' or `|'
is 4.