mbed

"An open-source embedded operating system designed specifically for the "things" in the Internet of Things (IoT). It includes all the features you need to develop a connected product based on an ARM Cortex-M microcontroller. mbed OS accelerates the process of creating a connected product by providing a platform operating system that includes robust security foundations, standards based communication capabilities, built-in cloud management services, and drivers for sensors, I/O devices and connectivity.

mbed OS is built as a modular, configurable software stack so that you can readily customize it to the device you're developing for, and reduce memory requirements by excluding unnecessary software components.

https://github.com/ARMmbed/mbed-os

https://www.mbed.com/en/

"mbed CLI is the name of the ARM mbed command-line tool, packaged as mbed-cli, which enables the full mbed workflow: repositories version control, maintaining dependencies, publishing code, updating from remotely hosted repositories (GitHub, GitLab and mbed.org) and invoking ARM mbed's own build system and export functions, among other operations."

https://github.com/ARMmbed/mbed-cli