How do I do the reverse of gitk's "Write commit to file"?
git, git-commit, gitk
Solution
I'm using Linux, but I think I see what you're talking about. In `gitk` there is a "Write commit to file" option when right-clicking a commit, which brings up a dialog that performs the command `git diff-tree --stdin -p --pretty` by default.
`git apply` is only for applying diffs, i.e. it won't create the commit object so that shouldn't be used. `git am` should be the correct tool for performing this operation, as it creates commit objects. However, it doesn't understand the format output by the above command, and creates the error you are seeing.
The easiest option is probably to create the patch using a format `git am` understands using `git format-patch` instead of `git diff-tree`. There may be a way to coerce `git am` into understanding the `git diff-tree` format, but I don't do patches much so am not aware of it offhand.
Problem
I have written a commit to a file from `gitk` by right-clicking the commit and selecting "Write commit to file". How do I apply the commit from this file? I can do `git apply`, `git add` and `git commit` combo, but isn't there a one-step command to just take the output (with the commit message and meta-data) and commit it as it is?