STM32F030F4 dev on Linux
Go to the STM32F030F4 page on ST's website and click on the Design Resources tab. Download Application Note AN4062 ("STM32F0DISCOVERY peripheral firmware examples") and its accompanying firmware package here. The firmware package has 21 examples and preconfigured projects for 4 different IDEs, and includes a GPIO toggle example.

You might also want to read AN4080 ("Getting started with STM32F0xxx hardware development") if you're not sure about your hardware design.

Using one of the IDEs is probably the easiest way to get started. Some of them allow you to work on small (code size limited) projects without buying the license. The Design Resources page has links to many of the common ones out there.