Say I've made a number of unrelated changes to uncoupled files in my git repo. I want to review and commit each of the files separately.
I run magit-status, and get a list of changed files. But the only magit diff commands I can find (d and D) diff entire revisons, not individual files.
I want the output of git diff <filename>, but in the magit diff buffer. How can I get magit to diff only one file?
Magit enables you to "review and commit each of the files separately" directly from the magit-status buffer, without the need for any separate diff buffers.
You just expand the file(s) you're interested in (with TAB, which shows you the diff for the file at point); then you can stage the bits of it that you want to commit (either the whole file, or individual hunks, or even a marked region) with s to stage (or u to unstage). Repeat for all the changes involved in that commit and, once everything necessary has been staged, press c to begin the commit.
You might prefer the visibility cycling behaviour you get by using C-TAB (repeatedly) instead of the simple toggle you get by default with TAB.
If you really do want to view the diff for a file in a separate buffer, you can do that from the file's buffer by calling magit-diff-buffer-file directly, or using the "diff" option (d) in magit-file-popup. e.g.:
(global-set-key (kbd "C-c m d") 'magit-diff-buffer-file)
(global-set-key (kbd "C-c m f") 'magit-file-popup)
Also note @assem's comment below:
You might also be interested in
magit-ediffwhich is bound to e by default, and opens an ediff session for the diff/file at point.
Some other alternatives available in Emacs by default (i.e. not Magit) are:
vc-diffvc-ediff for the ediff equivalentediff-revision to create an ediff session with more optionsI bind vc-ediff to C-xvC-= so that the two variants have similar key bindings.