Cortland Klein

I was inspired by Time Machine for every Unix out there to use the link-dest technique for backing up one external disk to another, however I found some limitations in its implementation, so I modified the script.

1. Moved Source and Destination into variables.
2. Added a Progress directory so the script can be interrupted and resumed.
3. Added an exclude file to the Source directory so that the External disk’s special folders (Spotlight, etc) are not copied.
4. Added the -E flag to rsync so it copies Extended Attributes on Mac OS X (remove if you are not using Mac OS X).
5. Added the -x flag to rsync so it does not span disks.
6. Added the –delete flag to rsync so if rsync fails upon re-running the script files deleted from the source are deleted from the Progress directory.
7. Modified the Date format to mimic Time Machine’s.
8. Modified the Destination so that it directly uses it rather than a subdirectory.
9. Modified the symbolic link command so it removes the old Latest link and creates the new one in one step.
10. Use && to ensure commands don’t occur if rsync fails.

The script (Updated to fix bug):

#!/bin/sh

source="/Volumes/Gray"
destination="/Volumes/Gray Backup"

mkdir -p "$destination/Progress"
rsync -aPEx --delete --exclude-from="$source/.exclude" \
            --link-dest="$destination/Latest" \
            "$source" "$destination/Progress" \
    && date=`date "+%Y-%m-%d-%H%M%S"` \
    && mv "$destination/Progress" "$destination/$date" \
    && ln -sfh "$date" "$destination/Latest"