How to create submodule in existing repo

Question

I'm beginner to git & I have the following folder structure for new project, so what I did is I went to visual studio and I made empty project it has this folder structure:

project: (Repo) 
folder1 (sub1)
folder2 (sub2)

I'm using git locally.
I created a repo for project using sourcetree,
now I cannot add any submodule, I don't know why.

In powershell whenever I try:

PS E:\Projects\Project> git submodule add ./sub1

I get the following error:

sub1 already exists in the index

then I decided to remove sub1 using git rm -r sub1,and add it again, then when I tried to add it again using git submodule add again, I received this new error:

sub1 already exists and is not a valid git repo

So what I'm doing wrong?

Answer 1

You simply need to be in your root folder and then add the submodule folder.

git submodule add <url>

Now when you clone the project you simply need to init and update the submodule

git submodule init
git submodule update

Git 1.8.2 features a new option --remote

git submodule update --remote --merge

will fetch the latest changes from upstream in each submodule, merge them in, and check out the latest revision of the submodule. As [the docs][1] put it:

--remote

This option is only valid for the update command. Instead of using the superproject’s recorded SHA-1 to update the submodule, use the status of the submodule’s remote-tracking branch.

This is equivalent to running git pull in each submodule.