Schedule

Schedule

Where things live

• Plist: Library/LaunchAgents/com.landonschropp.<name>.plist in the ~/.dotfiles repo, rcup-linked to ~/Library/LaunchAgents
• Logs: ~/Library/Logs/com.landonschropp.<name>/{stdout,stderr}.log, set via StandardOutPath/StandardErrorPath

Plist template

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>Label</key>
    <string>com.landonschropp.NAME</string>
    <key>ProgramArguments</key>
    <array>
      <string>/bin/zsh</string>
      <string>-lc</string>
      <string>COMMAND</string>
    </array>
    <key>StandardOutPath</key>
    <string>/Users/landon/Library/Logs/com.landonschropp.NAME/stdout.log</string>
    <key>StandardErrorPath</key>
    <string>/Users/landon/Library/Logs/com.landonschropp.NAME/stderr.log</string>
    <key>StartCalendarInterval</key>
    <array>
      <dict>
        <key>Hour</key>
        <integer>7</integer>
      </dict>
    </array>
  </dict>
</plist>

REQUIRED: ProgramArguments MUST run the command through /bin/zsh -lc "COMMAND", never bare. launchd jobs skip the login shell, so PATH is missing ~/.local/bin and everything rcup manages. -lc sources the login profile, putting commands like sync-repositories on PATH.

Multiple trigger times

StartCalendarInterval is an array of dicts, not a single time. Each dict is one full trigger spec — Hour, Minute, Day, Weekday, Month, any subset; omitted fields are wildcards. The job fires whenever any dict fully matches. For "twice a day," add a second dict differing only in Hour. Hour isn't special — for a specific weekday or minute, set that field on the dict that needs it.

Reload after editing

plutil -lint <plist>
~/.dotfiles/bin/set-up-launchd

Reloads every LaunchAgent, not just the edited one — fine, since every setup script in ~/.dotfiles is idempotent.

What launchd already handles — don't rebuild it

• No overlapping runs of the same job. Verified by testing: two triggers a minute apart, against a job that slept 90s, produced exactly one PID — the second was dropped, not queued. Don't add flock/lockf for this.
• Missed runs are deferred, not dropped. If the Mac is asleep at trigger time, man launchd.plist documents that it fires the job once on wake instead, coalescing everything missed in between into one catch-up run. No flag makes it drop instead.

So guard the script, not the schedule: make it idempotent (safe to run twice with no ill effect) rather than adding lock files or hour-checking guards to the plist.

Verify, don't assume

launchd docs and blog posts disagree on overlap and catch-up behavior. When it matters, test it directly: a throwaway /tmp plist, unique Label, trigger a minute or two out, command logs a timestamp+PID and sleeps past the next trigger. launchctl bootstrap gui/$(id -u) /tmp/test.plist, wait, read the log, then bootout and delete the scratch files.

Rationalizations