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Configuration keys

  • board_manager
    • additional_urls - the URLs to any additional Boards Manager package index files needed for your boards platforms.
  • daemon - options related to running Arduino CLI as a gRPC server.
    • port - TCP port used for gRPC client connections.
  • directories - directories used by Arduino CLI.
    • data - directory used to store Boards/Library Manager index files and Boards Manager platform installations.
    • downloads - directory used to stage downloaded archives during Boards/Library Manager installations.
    • user - the equivalent of the Arduino IDE's "sketchbook" directory. Library Manager installations are made to the libraries subdirectory of the user directory.
    • builtin.libraries - the libraries in this directory will be available to all platforms without the need for the user to install them, but with the lowest priority over other installed libraries with the same name, it's the equivalent of the Arduino IDE's bundled libraries directory.
    • - it's a list of directories of tools that will be available to all platforms without the need for the user to install them, it's the equivalent of the Arduino IDE 1.x bundled tools directory.
  • library - configuration options relating to Arduino libraries.
    • enable_unsafe_install - set to true to enable the use of the --git-url and --zip-file flags with arduino-cli lib install. These are considered "unsafe" installation methods because they allow installing files that have not passed through the Library Manager submission process.
  • locale - the language used by Arduino CLI to communicate to the user, the parameter is the language identifier in the standard POSIX format <language>[_<TERRITORY>[.<encoding>]] (for example it or it_IT, or it_IT.UTF-8).
  • logging - configuration options for Arduino CLI's logs.
    • file - path to the file where logs will be written.
    • format - output format for the logs. Allowed values are text or json.
    • level - messages with this level and above will be logged. Valid levels are: trace, debug, info, warn, error, fatal, panic.
  • metrics - settings related to the collection of data used for continued improvement of Arduino CLI.
    • addr - TCP port used for metrics communication.
    • enabled - controls the use of metrics.
  • output - settings related to text output.
    • no_color - ANSI color escape codes are added by default to the output. Set to true to disable colored text output.
  • sketch - configuration options relating to Arduino sketches.
  • updater - configuration options related to Arduino CLI updates
    • enable_notification - set to false to disable notifications of new Arduino CLI releases, defaults to true
  • build_cache configuration options related to the compilation cache
    • compilations_before_purge - interval, in number of compilations, at which the cache is purged, defaults to 10. When 0 the cache is never purged.
    • ttl - cache expiration time of build folders. If the cache is hit by a compilation the corresponding build files lifetime is renewed. The value format must be a valid input for time.ParseDuration(), defaults to 720h (30 days).

Configuration methods

Arduino CLI may be configured in three ways:

  1. Command line flags
  2. Environment variables
  3. Configuration file

If a configuration option is configured by multiple methods, the value set by the method highest on the above list overwrites the ones below it.

If a configuration option is not set, Arduino CLI uses a default value.

arduino-cli config dump displays the current configuration values.

Command line flags

Arduino CLI's command line flags are documented in the command line help and the Arduino CLI command reference.


Setting an additional Boards Manager URL using the --additional-urls command line flag:

$ arduino-cli core update-index --additional-urls

Environment variables

All configuration options can be set via environment variables. The variable names start with ARDUINO, followed by the configuration key names, with each component separated by _. For example, the ARDUINO_DIRECTORIES_USER environment variable sets the directories.user configuration option.

On Linux or macOS, you can use the export command to set environment variables. On Windows cmd, you can use the set command.

ARDUINO_BOARD_MANAGER_ADDITIONAL_URLS environment variables can be a list of space-separated URLs.


Setting an additional Boards Manager URL using the ARDUINO_BOARD_MANAGER_ADDITIONAL_URLS environment variable:


Setting multiple additional Boards Manager URLs using the ARDUINO_BOARD_MANAGER_ADDITIONAL_URLS environment variable:


Configuration file

arduino-cli config init creates or updates a configuration file with the current configuration settings.

This allows saving the options set by command line flags or environment variables. For example:

arduino-cli config init --additional-urls

File name

The configuration file must be named arduino-cli, with the appropriate file extension for the file's format.

Supported formats

arduino-cli config init creates a YAML file, however a variety of common formats are supported:


Configuration files in the following locations are recognized by Arduino CLI:

  1. Location specified by the --config-file command line flag
  2. Arduino CLI data directory (as configured by

If multiple configuration files are present, the one highest on the above list is used. Configuration files are not combined.

The location of the active configuration file can be determined by running the command:

arduino-cli config dump --verbose


Setting an additional Boards Manager URL using a YAML format configuration file:


Doing the same using a TOML format file:

additional_urls = [ "" ]

JSON schema

The configuration file JSON schema can be used to independently validate the file content. This schema should be considered unstable in this version.