Get a preview of "git add -u"?

Question

I'm trying to write a .gitignore file. I'd like to get a preview of everything that would be added if I were to run "git add -u". Is that possible? Or, if I ran "git add -u", and some stuff got added that I don't want, can I undo the entire thing? Then I'll tweak my .gitignore some more and repeat.

Thanks

Answer 1

I think you're looking for:

git add -n

.. which is the --dry-run short switch :)

Edit: from the root of the repository, try:

git add -n .

If you were to mistakenly add files that were supposed to be ignored, and you didn't catch it in the dry run, you'd just use:

git reset HEAD --

.. which would essentially unstage the files.

Answer 2

Note that the same preview won't work with an interractive add.

Git 2.32 (Q2 2021) is now clearer: "git add -i --dry-run"^(man) does not dry-run, which was surprising.
The combination of options has taught to error out.

See commit a1989cf (05 May 2021) by Øystein Walle (Osse).
^{(Merged by Junio C Hamano -- gitster -- in commit 47fa106, 14 May 2021)}

add: die if both --dry-run and --interactive are given

^{Signed-off-by: Øystein Walle}

The interactive machinery does not obey --dry-run.
Die appropriately if both flags are passed.

---

And: With Git 2.34 (Q4 2021), stop "git add --dry-run"^(man) from creating new blob and tree objects.

See commit e578d03 (12 Oct 2021) by René Scharfe (rscharfe).
^{(Merged by Junio C Hamano -- gitster -- in commit 6ffb5fc, 25 Oct 2021)}

add: don't write objects with --dry-run

^{Reported-by: [email protected]
Signed-off-by: René Scharfe}

When the option --dry-run/-n is given, "git add"^(man) doesn't change the index, but still writes out new object files.
Only hash the latter without writing instead to make the run as dry as possible.