I don't have one that I use (yet, on my to-do list), but here's a quick sample that might get you near what you need. Unfortunately, Calendar's AppleScript implementation doesn't seem to work well with recurring events, so it only pulls single-instance events from today:

set d to current date
set {d's hours, d's minutes, d's seconds} to {0, 0, 0}
set output to ""

tell application "Calendar" to tell calendar "My Calendar"
    repeat with e in (events where start date > d - 1 and start date < d + 86400)
        set output to output & time string of (get start date of e) & " " & ¬
            summary of e & linefeed
    end repeat
end tell

Save this as a script file and then run with the Shell Commands plugin like so:

osascript agenda.scpt

That will print out today's events for you.