mqtty 0.1.5

Bridges MQTT topics to a pseudo-terminal device

mqtty

mqtty bridges MQTT topics to either your local terminal or a pseudoterminal (PTY), and now also ships log capture and replay helpers for the same serial stream format.

This is useful for debugging, automation, or tunneling serial communication through a networked MQTT broker.

Commands

mqtty mqtt://<host>/<topic> [--pts-only]

mqtty runs in bidirectional terminal mode by default:

• bytes from stdin are published to .../device_serial_input
• bytes from .../device_serial_output are written to stdout
• if stdin is a TTY, it is placed into raw mode while mqtty is running
• type Ctrl-A Ctrl-X to exit, matching picocom's default exit sequence
• type Ctrl-A Ctrl-A to send a literal Ctrl-A

Use --pts-only if you only want a PTY device:

• --pts-only, -p: Print the path to the PTS device and keep it open without attaching local stdin/stdout. Useful for tools or scripts that want to use the virtual serial port.

mqtty-log records .../device_serial_output into replay files:

mqtty-log device mqtt://<host>/<serial-server>/<device> capture.jsonl.zst
mqtty-log prefix mqtt://<host>/<topic-prefix> logs/

• device records one full device URL into a single compressed replay file and adds .zst if omitted
• prefix subscribes to <topic-prefix>/#, keeps topics ending in device_serial_output, and rotates per-device logs under <outdir>/<topic-path-below-prefix>/YYYY-MM-DD_replay.jsonl.zst

mqtty-log-replay replays either plain or compressed replay logs:

mqtty-log-replay path/to/replay.jsonl.zst [--raw] [--follow] [--info]

Raw .jsonl logs are still accepted for replay and inspection.

The <topic> segment of the URI is used as the base path for MQTT messages across both live commands:

• .../device_serial_input receives bytes from local input and sends them to the device
• .../device_serial_output carries device output back to your terminal or PTY

Example

mqtty mqtt://broker.local/mydevice

This connects your terminal directly to mydevice/device_serial_input and mydevice/device_serial_output.

To expose a PTY instead:

mqtty mqtt://broker.local/mydevice --pts-only

This prints the local PTY path and keeps it bridged to the same MQTT topics until interrupted.

To capture a replay log while a device is running:

mqtty-log device mqtt://broker.local/mydevice mydevice.jsonl.zst

To capture every device under one serial-server or a broader base prefix:

mqtty-log prefix mqtt://broker.local/testbench/mark-pantry logs/
mqtty-log prefix mqtt://broker.local/testbench logs/

To inspect or replay that log later:

mqtty-log-replay mydevice.jsonl.zst --info
mqtty-log-replay mydevice.jsonl.zst

License

MIT