Install Arduino tools:

sudo apt install --reinstall arduino

Make sure your user id is in the “dialout” group.

The easiest way to install the Arduino command line utility is to download the latest release package from here, and just extract it into a directory in your path. It’s a single executable (built with Go), so it won’t clutter things up.

I used this as a reference. It has a lot more detail.

Before you run for the first time, create a configuration file:

arduino-cli config init

Create a new sketch:

arduino-cli sketch new MyFirstSketch

A boilerplate sketch file is generated for you:

MyFirstSketch.ino

void setup() {
}
 
void loop() {
}

Edit the generated file, and fill in some details:

MyFirstSketch.ino

void setup() {
    pinMode(LED_BUILTIN, OUTPUT);
}
 
void loop() {
    digitalWrite(LED_BUILTIN, HIGH);
    delay(1000);
    digitalWrite(LED_BUILTIN, LOW);
    delay(1000);
}

Update local cache of available platforms:

arduino-cli core update-index

After connecting your board, check to see if it’s recognized:

arduino-cli board list

Result should look something like this (I’m using an Uno):

Port         Type              Board Name  FQBN            Core       
/dev/ttyACM0 Serial Port (USB) Arduino Uno arduino:avr:uno arduino:avr

Install the core for your board (refer to the first two segments of the FQBN):

arduino-cli core install arduino:avr

Compile:

arduino-cli compile --fqbn arduino:avr:uno MyFirstSketch

Upload:

arduino-cli upload -p /dev/ttyACM0 --fqbn arduino:avr:uno MyFirstSketch

This Makefile simplifies the compile and upload steps, and adds format, reset, and clean commands:

Makefile

ARDCMD=arduino-cli
FQBNSTR=arduino:avr:uno
PORT=/dev/ttyACM0
SKETCHNAME=MyFirstSketch
FORMATTER=clang-format -i
 
default:
	@echo 'Targets:'
	@echo '  compile  -- Compile sketch, but don''t upload it.'
	@echo '  upload   -- Compile and upload sketch.'
	@echo '  format   -- Beautify your sketch code.'
	@echo '  reset    -- Use to resolve Device Busy error.'
	@echo '  clean    -- Remove binaries and object files.'
 
compile:
	$(ARDCMD) compile --fqbn $(FQBNSTR) $(SKETCHNAME)
 
upload: compile
	$(ARDCMD) upload -p $(PORT) --fqbn $(FQBNSTR) $(SKETCHNAME)
 
format:
	$(FORMATTER) $(SKETCHNAME)/$(SKETCHNAME).ino
 
reset:
	fuser -k $(PORT)
 
clean:
	-rm -f $(SKETCHNAME)/*.hex
	-rm -f $(SKETCHNAME)/*.elf