# Flipper Build Tool
FBT is the entry point for firmware-related commands and utilities.
It is invoked by `./fbt` in the firmware project root directory. Internally, it is a wrapper around [scons](https://scons.org/) build system.
If you don't need all features of `fbt` - like building the whole firmware - and only want to build and debug a single application, you can use [ufbt](https://pypi.org/project/ufbt/).
## Environment
To use `fbt`, you only need `git` installed in your system.
`fbt` by default downloads and unpacks a pre-built toolchain, and then modifies environment variables for itself to use it. It does not contaminate your global system's path with the toolchain.
> However, if you wish to use tools supplied with the toolchain outside `fbt`, you can open an *fbt shell*, with properly configured environment.
> - On Windows, simply run `scripts/toolchain/fbtenv.cmd`.
> - On Linux & MacOS, run `source scripts/toolchain/fbtenv.sh` in a new shell.
> - You can also type ```. `./fbt -s env` ``` in your shell. (Keep the "." at the beginning.)
If your system is not supported by pre-built toolchain variants or you want to use custom versions of dependencies, you can `set FBT_NOENV=1`. `fbt` will skip toolchain & environment configuration and will expect all tools to be available on your system's `PATH`. *(this option is not available on Windows)*
If `FBT_TOOLCHAIN_PATH` variable is set, `fbt` will use that directory to unpack toolchain into. By default, it downloads toolchain into `toolchain` subdirectory repo's root.
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