Regex Editor & Tester

Matches lines beginning with 'f' followed by up to 3 space-separated number groups, where each group is 1-2 digits optionally followed by slash-separated digits (e.g., 'f', 'f 12', 'f 12/31', 'f 1/2 3/4 5/6'). Useful for validating command prefixes with date-like or fractional arguments, with multiline flag enabled.