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Installing and Configuring b4

b4 is a utility for working with patches sent to a mailing list, such as

If you run nix-shell in the root of the Spectrum source tree, you’ll be dropped into a development shell that has b4 set up correctly, and you don’t need to do anything else. You only need to configure it manually as described here if you want it to work outside of the Spectrum root’s nix-shell.

Installing b4

You should be able to install b4 from your package manager.

Using Nix, you can start a shell with b4 available by running:

nix-shell -p b4

Configuring b4

As b4 was originally written for Linux development, it will default to searching for patches on the Linux mailing lists. So to use it for Spectrum, it needs to be configured to search the Spectrum mailing lists instead.

To do this, in a checkout of the appropriate git repository (Spectrum or Spectrum Nixpkgs), run:

git config b4.midmask

From now on, any b4 command run in Spectrum repositories will search the Spectrum devel mailing list.

Using b4

Using b4 to fetch and apply a patch from the Spectrum mailing list is described in the Testing Patches how-to guide.