Add Spotlight Comment from file?

Question

As I understand the way the *Add Spotlight Comments* works, the input is the file (or set of files) to be modified, and the added comments can either come statically from the workflow, or as user input if the workflow permits *Show Action When Run*.
I have a moderately ugly shell script that downloads and examines a succession of files and builds a description (just a few dozen words) that I want to add automatically to those comments. At the end of my script, I've downloaded the file, and stored the comments I want in a separate temp file.
As far as I can see, Automator can't do this: I can't specify a file as the incoming source of those new Spotlight Comments, can I?
Assuming the answer is negative, two quick non-Automator followups:
1) Is there any shell-script level Unix command that can manipulate the comments (without trying to hack into the .DS_Store files, that is).
2) Can Applescript do this? And, crucially, where's the best current help for Applescript for someone that hasn't touched it in many years?

Answer 1

Automator can do it, although some of the actions may not be obvious. Text (for example, the results of your ugly shell script) can be placed into a variable for later use, but you can also get it from a file. If your description/comment is in a plain text file, you can use the Combine Text Files action to get the text, then place it in a variable that can be used with the Set Spotlight Comments for Finder Items action.
Example:
1) Get Specified Finder Items (add your description file) (ignore input)
2) Combine Text Files
3) Set Value of Variable {Variable: whatever}
4) Get Specified Finder Items (add the file you want to comment) (ignore input)
5) Set Spotlight Comments for Finder Items {drag variable whatever to the text field, Append to existing comments}