Try Build - Tries to build selected files of an Arduino Sketch

arduino-trybuild.md

Try Arduino Build

Building Arduino sketches takes an imense amount of time. This is very annoying when fixing trivial issues like compile errors.

This tool tries to reduce your round-trip times by building only selected files of an Arduino Sketch.

Requirements

• arduino-cli - Arduino's build tool
• yq - a command line YAML parser

Demo

$ arduino-trybuild.sh Config.cpp WebUI.cpp
Reading build properties...
Using LIBRARIES from sketch.yaml: ArduinoJson ESP8266WiFi ESP8266HTTPClient ESP8266WebServer
Updating sketch sources...
'Property.h' -> '/home/mathias/.cache/arduino/sketches/213C467C5585CDE011EC1831BDC0F90C/sketch/Property.h'
Building 'WebUI.cpp'...
Building 'Config.cpp'...
$

Configuration

To make this all work that smoothly consider having an Arduino project file (called sketch.yaml) in your sketch:

default_fqbn: esp8266:esp8266:nodemcuv2:mmu=3232,baud=921600
libraries:
  - ArduinoJson
  - ESP8266WiFi
  - ESP8266HTTPClient
  - ESP8266WebServer

At least the default_fqbn can be created using arduino-cli board attach.

arduino-trybuild.sh

#!/bin/bash
# ---------------------------------------------------------------------
# Try Arduino Build - build selected files of a sketch
# ---------------------------------------------------------------------
# Copyright 2025 Mathias Hasselmann
# SPDX-License-Identifier: CC0-1.0
# ---------------------------------------------------------------------

# This function reports fatal errors and aborts.
# ---------------------------------------------------------------------
die() {
    echo "$@" >&2
    exit 1
}

# Check required dependencies
# ---------------------------------------------------------------------
which -s arduino-cli || die 'Could not find arduino-cli: https://github.com/arduino/arduino-cli'
which -s yq          || die 'Could not find yq: https://jqlang.org/'

# Read and cache build settings from arduino-cli
# ---------------------------------------------------------------------
build_setting() {
    key="$1"

    echo "${BUILD_PROPERTIES}" | sed -ne "s/^${key//./\\.}=//p"
}

echo "Reading build properties..."
BUILD_PROPERTIES=$(arduino-cli compile --show-properties)

echo "Building for '$(build_setting build.fqbn)'..."

BUILD_PATH=$(build_setting build.path)/sketch/
COMPILE_CPP=$(build_setting recipe.cpp.o.pattern)

CORE_INCLUDES=$(build_setting build.core.path)
VARIANT_INCLUDES=$(build_setting build.variant.path)
PLATFORM_LIBRARY_PATH=$(build_setting build.core.platform.path)/libraries

ARDUINO_HOME="${ARDUINO_HOME:-$(arduino-cli config get directories.user)}"
USER_LIBRARY_PATH="${USER_LIBRARY_PATH:-${ARDUINO_HOME}/libraries}"
SKETCH_CONFIG="${SKETCH_CONFIG:-sketch.yaml}"

# Resolve require libraries
# ---------------------------------------------------------------------
if [ -n "${LIBRARIES}" ]
then
    echo "Using LIBRARIES from environment variable: ${LIBRARIES}"
elif [ -r "${SKETCH_CONFIG}" ]
then
    LIBRARIES=$(yq -r '.["libraries"] | join(" ")' < "${SKETCH_CONFIG}")
    echo "Using LIBRARIES from "${SKETCH_CONFIG}": ${LIBRARIES}"
else
    echo "Could not find any library list in environment in environment or ${SKETCH_CONFIG}."
fi

# Resolve include directives
# ---------------------------------------------------------------------
library_includes() {
    separator=""

    for libname in "$@"
    do
        found=no

        for path in "${USER_LIBRARY_PATH}/${libname}/src" "${PLATFORM_LIBRARY_PATH}/${libname}/src"
        do
            if [ -d "${path}" ]
            then
                echo -n "${separator}-I '${path}'"
                separator=" "
                found=yes
                break
            fi
        done

        if [ "${found}" == "no" ]
        then
            echo "Library not found: ${libname}" >&2
            exit 1
        fi
    done
}

INCLUDES="-I '${CORE_INCLUDES}' -I '${VARIANT_INCLUDES}' $(library_includes ${LIBRARIES})" || exit 1

# Compile the selected sources
# ---------------------------------------------------------------------
echo "Updating sketch sources..."

cp -uv *.cpp *.h "${BUILD_PATH}"
test -d src && cp -ruv src "${BUILD_PATH}"

for file in "$@"
do
    echo "Building '${file}'..."
    compile_cpp="${COMPILE_CPP//\{includes\}/${INCLUDES}}"
    compile_cpp="${compile_cpp//\{source_file\}/${BUILD_PATH}${file}}"
    compile_cpp="${compile_cpp//\{object_file\}/${BUILD_PATH}${file/%.cpp/.o}}"
    compile_cpp="${compile_cpp//warnings\/none/warnings\/extra}"

    eval "${compile_cpp}"
done

# vim: sta sw=4 et