dnb-cal

A tiny macOS app that writes your Apple Calendar events for a date range to a file. It exists for scripts and helpers that can't ask for Calendar access themselves (Hammerspoon, SketchyBar, launchd jobs, cron): macOS gives Calendar access to apps, and asks for it under the app's own name, so DnbCal is an app.

brew install --cask drumandbytes/tap/dnb-cal

Use

open -g -n -a DnbCal --args 2026-10-29 2026-11-12 /tmp/events.tsv

The arguments are the first day, the last day (both included) and the output file. The first run asks for Calendar access for DnbCal (System Settings → Privacy & Security → Calendars). The output file is written in one step (temp file + rename), so it either doesn't exist yet or is complete. open -W can't reliably wait for an app that exits this quickly, so wait for the file instead.

One line per event, ordered by start, tab-separated:

2026-10-29	-	Rent due
2026-10-29	10:00	Standup

The date, the start time (HH:mm, or - for an all-day event) and the title. Recurring events are expanded. If access is refused the file contains just DENIED.

From Hammerspoon

os.remove(out)
hs.task.new("/usr/bin/open", nil, { "-g", "-n", "-a", "DnbCal", "--args", "2026-10-29", "2026-11-12", out }):start()
-- poll for `out`, read it, split lines on tabs

Why an app

A command-line tool run by Hammerspoon (or SketchyBar, launchd, …) counts as that program for macOS's privacy checks, so it needs that program to hold the permission, and Hammerspoon can't be given Calendar access (it doesn't declare a calendar usage description, so it never appears in the list). Started through open, DnbCal is its own app: it asks for access once under its own name and keeps it. Under the hood it's EventKit (requestFullAccessToEvents) and about 30 lines of code.

A note on signing

Ad-hoc signed, not notarized (a paid Apple Developer Program membership is the only way to change that). A Homebrew cask install goes through the normal one-time Gatekeeper approval, and because the signature changes with every release, macOS may ask for Calendar access again after an upgrade.

Build

swift build && swift test
scripts/build-app.sh [version]   # build/DnbCal.app, ad-hoc signed

Requires macOS 13+ (full-access Calendar permission on macOS 14+), Apple Silicon.