Question

I want to suppress all the output for files in

    dir/* 

when using the command

    git diff

I decided to follow the suggestions from
Excluding files from git-diff

Method 1.

Adding to .git/config

[alias]
    mydiff = !git diff -- $(git diff --name-only | grep -Ev "dir/")

and using

git mydiff

worked as expected and thus solved my problem. However, I wanted to use Method 2.

Method 2.

Adding to .gitattributes

dir/* -diff

and then using

git diff

Produces the output

diff --git a/dir/1 b/dir/1
deleted file mode 100644
index 05e9130..0000000
...

Question
How to suppress this undesired output for all the files in dir/?

Answer 1

The reason you see output with your settings is that dir/* -diff only marks files in dir as binary files, so text diff would not apply to them (see man 5 gitattributes).

To suppress any output for files in dir you have to define an external diff driver like this:

1. Assign new “silent” (you can choose your name) diff driver:

   $ cat .gitattributes 
   dir/* diff=silent
   

2. Define “silent” diff function:

   $ tail -n2 .git/config
   [diff "silent"]
       command = "true"
   

That should do the trick.