Find the last word in the given string and stores it in the property lastword.

    <regex pattern="(?'lastword'\w+)$" input="This is a test sentence" />
<echo message="${lastword}" />

Split the full filename and extension of a filename.

<regex pattern="^(?'filename'.*)\.(?'extension'\w+)$" input="d:\Temp\SomeDir\SomeDir\bla.xml" />

Split the path and the filename. (This checks for / or \ as the path separator).

<regex pattern="^(?'path'.*(\\|/)|(/|\\))(?'file'.*)$" input="d:\Temp\SomeDir\SomeDir\bla.xml" />

Results in path=d:\Temp\SomeDir\SomeDir\ and file=bla.xml.

The NAnt.Core.Tasks.RegexTask.Pattern attribute must contain one or more named grouping constructs, which represents the names of the properties to be set. These named grouping constructs can be enclosed by angle brackets (?<name>) or single quotes (?'name').