aconnect

aconnect [-dEeivVL] [-o|-i] [client:port] [client:port] ...

-d, --disconnect
    Delete specified connection(s).

-e, --exclusive
    Create exclusive connection (single input reader).

-E, --exclusive-unlock
    Unlock previously exclusive connection.

-i, --input
    List input ports only.

-o, --output
    List output ports only (default).

-L, --list-connections
    List current connections, not ports.

-v, --verbose
    Enable verbose output.

-V, --version
    Print version and exit.

-h, --help
    Show usage help.

aconnect is a command-line utility from the ALSA (Advanced Linux Sound Architecture) suite for listing, creating, and deleting connections between MIDI sequencer ports on Linux systems.

ALSA's sequencer provides a framework for routing MIDI events between software clients (like synthesizers, sequencers) and hardware devices. Each client has numbered ports; output ports send data, input ports receive it. Without connections, MIDI data doesn't flow between them.

Run aconnect alone or with -o to list output ports, -i for inputs, or -L for active connections. Connect ports with aconnect src_client:src_port dst_client:dst_port, enabling fan-out to multiple destinations. Use -d to disconnect, -e for exclusive links (single reader), or -E to unlock them.

Port IDs come from listings, e.g., 14:0 for a MIDI input, 128:0 for a virtual keyboard. Verbose mode (-v) aids debugging. Essential for MIDI routing in studios, it's lightweight and scriptable but requires ALSA permissions for some ports.

Client/port numbers from listings; system ports may need elevated privileges. Connections persist until disconnected or clients exit. No GUI; use qjackctl or aconnectgui for visuals.

aconnect -o
List available output ports.

aconnect -i
List input ports.

aconnect -L
Show active connections.

aconnect 14:0 128:0
Route MIDI from hw client 14 port 0 to synth client 128 port 0.

aconnect -d 14:0 128:0
Disconnect.

Ports shown as client_num:port_num (e.g., 128:0) or names if subscribed. Use aseqdump to monitor MIDI flow.

Introduced in ALSA 0.9.x (early 2000s) as part of alsa-utils; evolved with kernel sequencer API, now in alsa-utils 1.2.x for modern Linux distributions.

alsamixer(1), aseqdump(1), amidi(1), aplay(1)