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So installing vmware tools will give me command line access to the hypervisor though vCLI?
Yes. vmkfstools in vCLI has a remote connection option so you can do just that. There are other tools as well.
You can also rename a VMDK through the API with a reconfigVM_task(), but that's probably a bit more work than what you want to jump into. It's also low-level, so you have to understand the ReconfigSpec for the VM and backing types.
I was hoping to run vmkfstools to get around not having an api to do what i need to though there. Thanks this helps a lot. Are there any problems with using the cli when there are no api calls for vmkfstools?
Not sure I follow, but the vCLI vmkfstools will let you run the tool as if you were local to the host.