How do I undo ‘git add’ before git commit? Useful command to undo git add

Let’s assume by mistakenly you added file to git by using the command: git add, and you want to undo “git add before git commit?” Even this is the usual problem that you face in our day-to-day work as a Developer or DevOps or SysOps.

So what’s the real pullback from git add?

There are two options that will really do your job easy.

git reset HEAD <file> ?

or

git rm --cached <file>?

Let’s remember first what git add <file> it actually does:

1. If it <file> was not previously tracked, git add adds it to the cache , with its current content.
2. If <file> it’s already tracked, the git add current content (snapshot, version) is stored in the cache. 
3. In Git, this action is still called add, (not just update it), since two different versions (snapshots) of a file are treated as two different items: hence, we are indeed adding a new item to the cache so that it will eventually be committed later.

Considering this, the question is :

I added files by mistake using the command, git add , how I do undo before git commit ?

It ‘undo’ to remove the file (not just the current content) from the tracked items. If so, everything is fine git rm --cached <file>.

And we could run as well git reset HEAD <file>. I prefer this because it works in both scenarios: it also undoes when we mistakenly added a version of an already tracked item.

Example:

1- File1.txt created and by mistake index to git using git add command.

2- Undo the git add using git reset file1.txt and track file again using git status