Terraform: move resource between state files

When you have several terraform stacks to handle, it might happen that you realize that one resource is created in the incorrect stack. The easiest way to move it is usually to remove it from one stack, apply, then add it to the other stack, and apply again. But for some resources, this is solution is difficult to implement.
In my case, it was an S3 bucket, containing several big files. It would have been a long process to backup the files, destroy them from the bucket, then restore them on the destination bucket. So here is the way to move a resource between stacks without destroying it.

First, you have to pull your destination state file locally. Say you want to move your module my_bucket from a stack in folderA to another stack in folderB:

cd folderB terraform state pull > folderB.state

Second step, you have to move your resource to its new destination:

cd ../folderA terraform state mv -state-out ../folderB/folderB.state module.my_bucket module.my_bucket

The mv command takes the source and destination name of your resource as parameters, so it is possible to rename your resource as you move it. As the final step, you push your destination state file to its remote location:

cd ../folderB terraform state push folderB.state