git - How to maintain (mostly) parallel branches with only a few difference

Question

Scenario: I'm trying to get my unix dot-files under git. I have to work between (at least) the cygwin environment and some standard linux distros (ubuntu and opensuse), and I have files/lines of code that are only specific to, say, cygwin. Since I don't want to checkout useless files or have to deal with lots of cases inside my dotfiles, I'm creating branches for each of my environments. But most of the edits I do are common to all environments, so almost every time I made a commit I need to propagate that change to all my branches.

So basically I have several branches that are almost identical except for a few commits, and most commits I do need to be in all branches.

The question: what is the recommended git workflow for this, if there is any? Or is there a better setup (without using multiple branches?) for my scenario?

[I tried cherry-picking, but that involves quite a bit of work, and not to mention all the duplicate commits out here and the nightmare it is to keep my branches in sync.]

Answer 1

For that particular case, where there is a lot of common files evolving in one branch, and only a few config files specific per environment... we do not store the config file in Git. At all.

We do store template of said config files, plus all the specific per-environment values, plus a script able to replace the variables in the template files by the correct value (detecting the current platform)

That way, we do not need to make a branch only for those files.

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Another good way to manage those kind of files (with a platform-specifc content) is through a git attribute filter driver (see also Pro Git book).

A filter driver consists of a clean command and a smudge command, either of which can be left unspecified.
Upon checkout, when the smudge command is specified, the command is fed the blob object from its standard input, and its standard output is used to update the worktree file.
Similarly, the clean command is used to convert the contents of worktree file upon check-in.

That way, a script (managed with Git) referenced by the smudge can replace all the variables by platform-specific values, while the clean script will restore its content to an untouched config file.

The main idea remains: avoid creating branches only for that kind of parallel evolution.