[Bug-tar] One-file-system and listed-incremental again

[Peter Kronheimer]

Hi,

I am using

        tar --create --listed-incremental=list --one-file-system (etc.)

to perform full and incremental backups of my filesystem, with tar 
1.15.1. I tested my backups by making a restore to new partition:

        for TARFILE in [ $ORDERED_LIST_OF_TARFILES ] ; do
                tar --extract --one-file-system \
                --listed-incremental=/dev/null \
                --directory=/mnt/new \
                --file=$TARFILE
        done

I am aware of the new behaviour of "--one-file-system" and --extract in 
1.15: this version of tar will not purge directories on a "different" 
file system. However, the question is "different from what?"

Am I right in thinking that "different" means "different from the cwd in 
which tar is invoked"? My experience is that this is so. The result is 
that the above restore script fails to purge stuff that should be 
purged: everything that is restored by the script above is on the 
"different" device at /mnt/new.

Is this the intended behaviour? It worries me that this will bite a lot 
of people: when restoring a backup to a new hard disk, a command-line of 
the sort given above is a natural choice, but will fail to do what is 
wanted.

Many thanks,
Peter Kronheimer