fcbnerd is a command-line tool that turns any MIDI foot controller, like the Behringer FCB1010, into an extra input device for macOS. It connects to MIDI sources and either runs shell commands when specific footswitch or pedal messages are received, or outputs JSON events for other programs to process. Built for the FCB1010 but compatible with any Core MIDI source, it avoids sandbox permissions by only reading MIDI, delegating actions to the user's shell or tools like Hammerspoon.

Installation is available via Homebrew after trusting the tap, or from source using Swift on macOS 13+. Users can bind commands to MIDI events such as control changes or program changes, using patterns like '1:20:127=open ~/Downloads' to trigger actions. The tool supports real-time event streaming, hot-plugging, and simulated MIDI input for testing.

Output can be formatted as text for readability or JSON for scripting, with immediate flushing for pipe compatibility. Environment variables like MIDI_TYPE, MIDI_CHANNEL, and MIDI_VALUE are passed to bound commands, enabling dynamic responses such as adjusting volume via expression pedals.