Universal serial monitor for embedded devices.
Watch any number of ports simultaneously. Detect crashes and events by pattern.
Stream structured JSON to your pipeline. Log, react, automate.
curl -fsSL https://apt.espilon.net/espilon.gpg.key | sudo gpg --dearmor -o /etc/apt/trusted.gpg.d/espilon.gpg
echo "deb https://apt.espilon.net stable main" | sudo tee /etc/apt/sources.list.d/espilon.list
sudo apt update && sudo apt install emonbrew tap EspilonOrg/tap
brew install emonyay -S emon
# or: paru -S emongit clone https://github.com/EspilonOrg/emon && cd emon
make
PREFIX=~/.local make install # → ~/.local/bin/emon (no sudo needed)The only runtime dependency (libserialport) is vendored, no system packages required.
# Raw output from one device
emon /dev/ttyUSB0
# Color-coded events with an ESP32 pattern file
emon --verbose -p patterns/esp32.pat /dev/ttyUSB0
# Two devices, named, at the same time
emon --name /dev/ttyUSB0=ESP32 --name /dev/ttyACM0=Arduino \
/dev/ttyUSB0 /dev/ttyACM0Boot sequence and verbose serial output from an ESP32:
Type commands, capture events in real time, full bidirectional I/O:
emon -i -p patterns/arduino.pat /dev/ttyACM0| Shortcut | Action |
|---|---|
Ctrl+C |
Quit |
Ctrl+A X |
Quit |
Ctrl+A C |
Send raw 0x03 to device |
Pure NDJSON on stdout, pipe anywhere:
emon --quiet --json-events -p patterns/arduino.pat /dev/ttyACM0 | jq .Each event:
{"rule": "OOM", "severity": "CRITICAL", "device": "ttyACM0", "line": "...", "ts": 1718000000000}Two devices, each color-coded, in one terminal:
emon --verbose \
--name /dev/ttyUSB0=ESP32 \
--name /dev/ttyACM0=Arduino \
/dev/ttyUSB0 /dev/ttyACM0Detach, collect logs, inspect later:
emon --bg --logdir ./logs -p patterns/esp32.pat /dev/ttyUSB0
emon status # running (PID 12345)
emon stop # graceful shutdown
cat logs/ttyUSB0.log# patterns/esp32.pat
CRITICAL GURU_MEDITATION Guru Meditation Error
CRITICAL ABORT abort\(\) was called
HIGH STACK_OVERFLOW stack overflow
WARN RESET rst:0x
INFO BOOT I \([0-9]+\) boot:
Format: SEVERITY NAME REGEX, one rule per line, POSIX extended regex.
Severities: CRITICAL › HIGH › WARN › INFO
Built-in families: esp32 · stm32 · arduino · freertos · zephyr · esp-idf · exploit
See CONTRIBUTING.md to add a new family, no C required, just a .pat file.
CI integration: exit with the right code when a rule fires or times out:
emon --wait-for BOOT_OK --timeout 30 /dev/ttyUSB0 # exit 0 on match, 124 on timeout
emon --exit-on "PANIC=1" --timeout 60 /dev/ttyUSB0 # exit 1 on PANICEvent hooks: fire a Python script on every match:
emon --on-event hooks/alert.py -p patterns/esp32.pat /dev/ttyUSB0emon passes a JSON payload on stdin. Fire-and-forget, the monitor never blocks.
See docs/hooks.md for ready-made ntfy, Slack, Discord, and SQLite examples.
Auto-detect: load the right pattern file automatically from USB VID/PID:
emon --auto-patterns patterns/ /dev/ttyUSB0Config file: persist all flags in an INI file:
# .emon.conf
baud = 115200
logdir = ./logs
pattern = patterns/esp32.pat
on_event = hooks/alert.pyemon --config .emon.conf /dev/ttyUSB0Full reference: .emon.conf.example
src/
app/ config parsing, daemon mode
monitor/ main loop, pattern detector, event recorder
serial/ libserialport I/O, USB auto-detect, hardware reset
ui/ display, TUI, hex dump, interactive mode
patterns/ .pat rule files per device family
tests/ unit tests (51), hardware test harness
vendor/ vendored libserialport (static, no system install)
One pthread per port. Pattern detection uses POSIX regex with an open-addressing hash set (FNV-1a, 2048 slots) for O(1) deduplication. No ncurses, native ANSI only.
See CONTRIBUTING.md.
The easiest contribution is a new .pat pattern file for a device family you use.
Apache 2.0, see LICENSE.
Part of the Espilon Association open source ecosystem.