[git] How to change the remote repository for a git submodule?

I've created a git repository with a submodule in it. I'm able to tell the submodule itself to change its remote repository path, but I'm not sure how to tell the parent repository how to change the remote repository path for the submodule.

I wouldn't be surprised if I'm somewhat out of luck and have to do things manually, as even deleting submodules isn't easy.

In simple terms, you just need to edit the .gitmodules file, then resync and update:

Edit the file, either via a git command or directly:

git config --file=.gitmodules -e

or just:

vim .gitmodules

then resync and update:

git submodule sync
git submodule update --init --recursive --remote

Just edit your .git/config file. For example; if you have a "common" submodule you can do this in the super-module:

git config submodule.common.url /data/my_local_common

You should just be able to edit the .gitmodules file to update the URL and then run git submodule sync --recursive to reflect that change to the superproject and your working copy.

Then you need to go to the .git/modules/path_to_submodule dir and change its config file to update git path.

If repo history is different then you need to checkout new branch manually:

git submodule sync --recursive
cd <submodule_dir> 

git fetch
git checkout origin/master
git branch master -f
git checkout master

With Git 2.25 (Q1 2020), you can modify it.
See "Git submodule url changed" and the new command

git submodule set-url [--] <path> <newurl>

Original answer (May 2009, ten years ago)

Actually, a patch has been submitted in April 2009 to clarify gitmodule role.

So now the gitmodule documentation does not yet include:

The .gitmodules file, located in the top-level directory of a git working tree, is a text file with a syntax matching the requirements -of linkgit:git-config1.
[NEW]:
As this file is managed by Git, it tracks the +records of a project's submodules.
Information stored in this file is used as a hint to prime the authoritative version of the record stored in the project configuration file.
User specific record changes (e.g. to account for differences in submodule URLs due to networking situations) should be made to the configuration file, while record changes to be propagated (e.g. +due to a relocation of the submodule source) should be made to this file.

That pretty much confirm Jim's answer.

If you follow this git submodule tutorial, you see you need a "git submodule init" to add the submodule repository URLs to .git/config.

"git submodule sync" has been added in August 2008 precisely to make that task easier when URL changes (especially if the number of submodules is important).
The associate script with that command is straightforward enough:

module_list "$@" |
while read mode sha1 stage path
do
    name=$(module_name "$path")
    url=$(git config -f .gitmodules --get submodule."$name".url)
    if test -e "$path"/.git
    then
    (
        unset GIT_DIR
        cd "$path"
        remote=$(get_default_remote)
        say "Synchronizing submodule url for '$name'"
        git config remote."$remote".url "$url"
    )
    fi
done

The goal remains: git config remote."$remote".url "$url"

git config --file=.gitmodules -e opens the default editor in which you can update the path

A brute force approach:

• update the .gitmodules file in the supermodule to point to the new submodule url,
• add and commit the changes to supermodule/.gitmodules,
• make a new clone of the supermodule somewhere else on your computer (making sure that the latest changes to the .gitmodules file are reflected in the clone),
• change your working directory to the new clone of the supermodule,
• run git submodule update --init path-to-submodule on the submodule,

et voilà! The submodule in the new clone of the supermodule is properly configured!

What worked for me (on Windows, using git version 1.8.3.msysgit.0):

• Update .gitmodules with the URL to the new repository
• Remove the corresponding line from the ".git/config" file
• Delete the corresponding directory in the ".git/modules/external" directory (".git/modules" for recent git versions)
• Delete the checked out submodule directory itself (unsure if this is necessary)
• Run git submodule init and git submodule update
• Make sure the checked out submodule is at the correct commit, and commit that, since it's likely that the hash will be different

After doing all that, everything is in the state I would expect. I imagine other users of the repository will have similar pain when they come to update though - it would be wise to explain these steps in your commit message!

These commands will do the work on command prompt without altering any files on local repository

git config --file=.gitmodules submodule.Submod.url https://github.com/username/ABC.git
git config --file=.gitmodules submodule.Submod.branch Development
git submodule sync
git submodule update --init --recursive --remote

Please look at the blog for screenshots: Changing GIT submodules URL/Branch to other URL/branch of same repository