F.4 Tips on using regular expressions

Bear these in mind when specifying regular expressions.

When specified as a regular expression, a period followed by an asterisk (.*) will match any characters. If you use this combination frequently, it might take a long time to find the matches. When you are searching for a long message, for example, use the period and asterisk combination only where required in the search string.
To find matches with non-null characters in UNIX, you can reduce the search time by using the combination [^ ]*. This expression matches repetitions of non-null characters.