reDOTALL

reDOTALL refers to the DOTALL flag in Python's standard library for regular expressions, the re module. When enabled, the dot character in a regex pattern matches any character, including the newline character. Without DOTALL, the dot matches any character except a newline.

The flag is exposed as re.DOTALL and has the alias re.S. It can be passed to regex functions such as compile, search, and match, or used inline in the pattern as (?s). For example, text = "Line1\nLine2"; pattern = r"Line1.*Line2"; using re.search(pattern, text, re.DOTALL) will find a match because the dot can span the newline, whereas without DOTALL the match would fail.

DOTALL affects only the behavior of the dot; it does not by itself change the behavior of anchors. If you also need line-based anchors, you can combine DOTALL with re.MULTILINE. In that case, ^ and $ still have their multiline behavior, while the dot can still cross newlines.

Common uses of reDOTALL include parsing multi-line strings, blocks of text, or log entries where the target pattern may extend across several lines. It is often used when the content of interest is not confined to a single line and the pattern should consider the entire span of text between markers.

Related concepts include re.MULTILINE for line anchors and the inline form (?s) to enable DOTALL directly in the pattern. In other languages, similar options exist under names such as Pattern.DOTALL (Java) or RegexOptions.Singleline (.NET).