Script code or Airtable no-code automation? There's not a way to import/export automations between bases, likely because automations are very dependent on relevant base data to create/test them and it's not a process you would need to do very often.

If you're an Enterprise plan, you could theoretically 2-way sync to an automation base that runs automations and syncs the edits back but it would probably be slower than running the automations in each base. Non-enterprise plans do not have 2-way sync.

I am just trying to find a way to share common code across bases.  I don't need to import  Automations. I'd like to import a bunch of common scripts that I want to use in multiple  places/bases  without needing to  duplicate  them

Yeah there's not a way to copy extensions/dashboards from one base to another, only within the same base.

You could duplicate the base and move tables from an existing base to it but that's probably not faster than just copying and pasting the scripts manually. If you want to add a bunch of extensions somewhat quickly, you can with the manage extensions button by clicking the ... and duplicating a script extension (adding is slower):

Scripts cannot be shared across bases. You have to manually copy/paste the script in all the locations where you want to use it.

If your script uses hardcoded table or field names, make sure they are the same across all bases, or you will have to make changes to the scripts anyway.