Renaming image files in remote container?

I am running FM Server 12 Advanced. I have a container field with it's images being stored externally in a folder on the same server. I have a text field which contains the new name that I would like to apply to each photo. Can I rename the files from a client running on a different computer?

I found this thread from a couple of years ago which explains a way that this can be done with the 30works Scriptmaster plugin.

Can some please explain how to create the function that he is referring to in this comment? I do not have any experience with creating custom functions and it's not clear to me how proceed. Thanks.

There is an object ScriptMaster creates and has access to (fmpro) that can be used to accomplish this.

You'll use two input parameters ("fully qualified original container field name" and "new filename"). The code is extremely simple:

return fmpro.getAsContainer(fmpro.getContainerStream(fieldName), fileName);

Once you have created the function you'll want to call it using a Set Field step on the output container field. The result of the function is FM Binary and the filename. You can add use the ScriptMaster sample file to test this.