aconnect

List all MIDI input and output ports

$ aconnect -l

$ aconnect [sender_client]:[port] [receiver_client]:[port]

$ aconnect -d [sender_client]:[port] [receiver_client]:[port]

$ aconnect -x

$ aconnect -i

aconnect [-l] [-i] [-o] [sender] [receiver]

aconnect is an ALSA (Advanced Linux Sound Architecture) utility for connecting and disconnecting MIDI ports. It manages the ALSA sequencer connections that route MIDI data between applications, hardware MIDI interfaces, and virtual MIDI ports.
The tool is essential for setting up MIDI routing in Linux audio workflows, allowing you to connect MIDI controllers to synthesizers, route between DAWs, or chain MIDI effects processors.

-l, --list

List current MIDI ports and connections

List only input (readable) ports

List only output (writable) ports

Disconnect the specified ports

Remove all connections

Connect ports exclusively (no other connections allowed)

Connections made with aconnect are not persistent; they're lost when the MIDI device is disconnected or the system reboots. For persistent connections, use tools like qjackctl or write startup scripts. Client numbers may change between sessions.

aconnect was developed as part of the ALSA project in the late 1990s. It provided a command-line interface for the ALSA sequencer system, which replaced the older OSS (Open Sound System) MIDI handling in Linux.

amidi(1), aplaymidi(1), arecordmidi(1), aseqdump(1)