A regular expression (sometimes called a “pattern”) is a find string that uses special characters to match patterns of text. You can use regular expressions to find patterns such as five-digit numbers or strings in quotation marks. Selected portions of found text can be used in a replacement.
In PWB you can specify regular expressions in two ways: UNIX syntax and non-UNIX syntax. UNIX regular expressions have a syntax similar to regular expressions in the UNIX and XENIX operating systems. CodeView uses a subset of the UNIX regular-expression syntax. Non-UNIX regular-expression syntax has the features of UNIX regular expressions but includes additional features and uses a more compact syntax.
The Unixre switch determines whether PWB uses UNIX or non-UNIX regular expressions in searches. PWB switches that accept regular expressions, such as Build and Word, always use UNIX syntax.