How can I debug an Automator workflow?

I have a very simple automator action consisting on a shell script that should be executed in a selected folder in the finder. When I execute the action I get the message:

The action "Run Shell Script" encountered an error.

Obviously this is too generic. Is there an easy way to see a more precise error message that give me a clue of what the problem is about ?

Solution 1:

Enable the Automator Log

Automator's Log panel should display more detailed error information. You can show it by clicking the Log item in the View menu (or pressing ⌥⌘L).

Solution 2:

If you need to debug workflow outside of Automator.app, then syslog command can be used.

Say you made Quick Action workflow with Run Shell Script action like below:

for f in "$@"
do
    syslog -s -l i "Touching file: $f"
    touch "$f"
done

Now you can use Quick Action in Finder:

Output of syslog command can be viewed in Console.app:

Another way to view output of syslog command – is to use log command in Terminal.app.

log stream --info --debug --predicate 'process == "syslog"'

Update

We can improve Quick Action shown above by sending local notification on successful completion:

for f in "$@"
do
    syslog -s -l i "Touching file: $f"
    touch "$f" || exit 1 # Early exit on failure.
    osascript -e "display notification \"Touched file: $f \" with title \"Automation\""
done

Solution 3:

If you're willing to use JavaScript via the Run JavaScript action rather than shell scripting, you can get pretty great step-through debugging features that web devs nowadays are used to, i.e. the Web browser Inspect panel (in this case Safari's). Setup guide available in Apple's docs on debugging Automator JS.

Setup is simple and as of this comment is verified working on Big Sur.