# mechanicaldiff

`mechanicaldiff` lets you filter down a diff to _only_ the parts that make a specific mechanical change, so you can commit those changes separately.

Usage: `git diff | mechanicaldiff <pattern> <replacement>`

It differs from [grepdiff](https://linux.die.net/man/1/grepdiff) in that it doesn’t just search for the lines that contain the given `pattern`, but also checks that the _only_ change in that line is that `pattern` was replaced with the given `replacement`.

It differs from simply replacing `pattern` with `replacement` in the entire repository in that it filters down an _existing_ diff, which means that the resulting diff doesn’t make the mechanical change everywhere, but only in the lines that your original diff also made it.