abc is a simple, yet powerful, textual musical notation. This paper presents abc::dt, a rule-based domain-specific language (Perl embedded), designed to simplify the creation of abc processing tools. Inspired by the Unix philosophy, those tools intend to be simple and compositional in a Unix filters' way. From abc::dt's rules we obtain an abc processing tool whose main algorithm follows a traditional compiler architecture, thus consisting of three stages: 1) abc parser (based on abcmtops' parser), 2) abc semantic transformation (associated with abc attributes), 3) output generation (either a user defined or system provided abc generator).