Automatic Backup of USB Drive

I’ve started to keep some regularly-updated critical information on my USB thumb drive. Apple’s Time Machine doesn’t seem to be willing to back up external disks (or at least VFAT-formatted external disks). I figured I’d piggyback on Time Machine’s hourly backups by using rsync to copy the thumb drive periodically to my MacBook’s hard drive. OS X 10.5 still supports cron, but I keep running across references to launchd. After some googling, I came up with the following script:

#!/bin/bash
test -e /Volumes/MCZ &&
  rsync -avr --delete /Volumes/MCZ $HOME/Metabackup/ >& $HOME/Metabackup/MCZ.log

and the following plist describing the new “service” I wanted launchd to handle:

<?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>KeepAlive</key>
        <false/>
        <key>Label</key>
        <string>znet.backups.mczthumb</string>
        <key>ProgramArguments</key>
        <array>
                <string>/bin/bash</string>
                <string>/Users/mzwier/bin/backup-thumb.sh</string>
        </array>
        <key>RunAtLoad</key>
        <true/>
        <key>StartCalendarInterval</key>
        <dict>
                <key>Minute</key>
                <integer>52</integer>
        </dict>
</dict>
</plist>

This is exactly equivalent to the cron line

52 * * * * /bin/bash /Users/mzwier/bin/backup-thumb.sh

I saved the plist in ~/Library/LaunchAgents (as znet.backups.mczthumb) and ran launchctl:

launchd% load /Users/mzwier/Library/LaunchAgents/znet.backups.mczthumb

Worked on the first try. It may be useful to perform an update every time the drive is mounted, but that’s a challenge for another day.

Explore posts in the same categories: Computing

Tags: OS X

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