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MacOS - Automate Tasks via launchd

2 min read

Apple actually deprecated cron years ago in favor of Launch Agents (launchd). Launchd service of Apple fixes the missing issue of cron. Suppose that you have a scheduled cron job that runs everyday at 14:00. In practice, the command can be executed, if your machine is turned on. Otherwise, the command cannot be executed. The macOS system launcher has a built-in catch-up feature: if your Mac is sleeping when a scheduled event comes around, it will automatically run the task as soon as the Mac wakes up.

1. Create a launch agent file in your user directory:

nano ~/Library/LaunchAgents/com.alptugan.githubbackup.plist

2. Paste this XML configuration (adjusting the script path if necessary):

<?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.alptugan.githubbackup</string>
 
	<key>ProgramArguments</key>
	<array>
		<string>/bin/sh</string>
		<string>/Users/alptugan/Documents/DEVS/scripts/backup_dotfiles</string>
	</array>
 
	<!-- Run every Sunday at 10:00 AM -->
	<key>StartCalendarInterval</key>
	<dict>
		<key>Weekday</key>
		<integer>0</integer> <!-- 0 = Sunday -->
		<key>Hour</key>
		<integer>10</integer>
		<key>Minute</key>
		<integer>0</integer>
	</dict>
 
	<key>StandardOutPath</key>
	<string>/Users/alptugan/Documents/Obsidian/backup.log</string>
	<key>StandardErrorPath</key>
	<string>/Users/alptugan/Documents/Obsidian/backup_error.log</string>
</dict>
</plist>

Another example make the script runs every 10 hours on everyday.

<?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.alptugan.obsidiansync</string>
 
    <key>ProgramArguments</key>
    <array>
        <string>/bin/sh</string>
        <string>/Users/alptugan/Documents/DEVS/scripts/obsidian_sync</string>
    </array>
 
    <!-- Run every 10 hours (36,000 seconds) -->
    <key>StartInterval</key>
    <integer>36000</integer>
 
    <!-- Run immediately when loaded or on boot -->
    <key>RunAtLoad</key>
    <true/>
 
    <key>StandardOutPath</key>
    <string>/Users/alptugan/Documents/Obsidian/obsidian_sync.log</string>
    <key>StandardErrorPath</key>
    <string>/Users/alptugan/Documents/Obsidian/obsidian_sync_error.log</string>
</dict>
</plist>

3. Verify The Syntax

plutil ~/Library/LaunchAgents/com.alptugan.obsidian_sync.plist
 
# (It should output `OK` now).

4. Check Status

launchctl list | grep com.alptugan.obsidian_sync
 
# You should see a PID or an exit status of `0` in the output!

5. The Fix: Give /bin/sh Full Disk Access

You need to explicitly allow /bin/sh to access files in system and user directories when running as a background service.

  1. Open System Settings > Privacy & Security > Full Disk Access.

  2. Click the + button at the bottom (you may need to enter your Mac password or Touch ID).

  3. Press CMD + SHIFT + G to open the path drawer.

  4. Type /bin/sh and hit Enter.

  5. Select sh and click Open.

  6. Ensure the toggle switch next to sh is set to ON.

6. Load the agent so macOS registers it:

launchctl load ~/Library/LaunchAgents/com.alptugan.githubbackup.plist

7. Kickstart the agent to test

launchctl kickstart -k gui/$(id -u)/com.alptugan.obsidian_sync

If you need to change the file name or refresh the loaded agent, execute the boot out command to refresh launchd.

launchctl bootout gui/$(id -u)/com.alptugan.obsidian_sync 2>/dev/null
launchctl bootstrap gui/$(id -u) ~/Library/LaunchAgents/com.alptugan.obsidian_sync.plist

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