[git] How do I 'git diff' on a certain directory?

git diff actually runs a diff on all source code. How do I do this on a certain directory, so that I can view modifications on files underneath it?

What I was looking for was this:

git diff <ref1>..<ref2> <dirname>

Not only you can add a path, but you can add git diff --relative to get result relative to that folder.

git -C a/folder diff --relative

And with Git 2.28 (Q3 2020), the commands in the "diff" family learned to honor the "diff.relative" configuration variable.

See commit c28ded8 (22 May 2020) by Laurent Arnoud (spk).
^{(Merged by Junio C Hamano -- gitster -- in commit e34df9a, 02 Jun 2020)}

diff: add config option relative

^{Signed-off-by: Laurent Arnoud
Acked-by: Ðoàn Tr?n Công Danh}

The diff.relative boolean option set to true shows only changes in the current directory/value specified by the path argument of the relative option and shows pathnames relative to the aforementioned directory.

Teach --no-relative to override earlier --relative

Add for git-format-patch(1) options documentation --relative and --no-relative

The documentation now includes:

diff.relative:

If set to 'true', 'git diff' does not show changes outside of the directory and show pathnames relative to the current directory.

If you're comparing different branches, you need to use -- to separate a Git revision from a filesystem path. For example, with two local branches, master and bryan-working:

$ git diff master -- AFolderOfCode/ bryan-working -- AFolderOfCode/

Or from a local branch to a remote:

$ git diff master -- AFolderOfCode/ origin/master -- AFolderOfCode/

Add Beyond Compare as your difftool in Git and add an alias for diffdir as:

git config --global alias.diffdir = "difftool --dir-diff --tool=bc3 --no-prompt"

Get the gitdiff as:

git diffdir 4bc7ba80edf6  7f566710c7

Reference: Compare entire directories w git difftool + Beyond Compare

If you want to exclude the sub-directories, you can use

git diff <ref1>..<ref2> -- $(git diff <ref1>..<ref2> --name-only | grep -v /)

To use Beyond Compare as the difftool for directory diff, remember enable follow symbolic links like so:

In a Folder Compare View → Rules (Referee Icon):

And then, enable follow symbolic links and update session defaults:

OR,

set up the alias like so:

git config --global alias.diffdir "difftool --dir-diff --tool=bc3 --no-prompt --no-symlinks"

Note that in either case, any edits made to the side (left or right) that refers to the current working tree are preserved.

You should make a habit of looking at the documentation for stuff like this. It's very useful and will improve your skills very quickly. Here's the relevant bit when you do git help diff

   git diff [options] [--no-index] [--] <path> <path>

The two <path>s are what you need to change to the directories in question.