Simulate incremental backups with tar

Prepare env:

$ mkdir test
$ cd test
$ cp /etc/hosts .
$ cp /etc/hostname .
$ cp /etc/services .
$ ls
$ cd ..

Backup day zero:

$ tar cvf my0.tar -g my.snar test
tar: test: Directory is new
test/
test/hostname
test/hosts
test/services

changes on second day and run backup for next day:

$ echo hi >> test/hosts
$ tar cvf my1.tar -g my.snar test
test/
test/hosts

Changes on next day and next incremental backup:

$ rm test/hostname
$ tar cvf my2.tar -g my.snar test
test/

Simulate a disaster:

rm -rf test

Restore day 0:

$ tar xvf my0.tar -g /dev/null
test/
test/hostname
test/hosts
test/services

Restore day 1:

$ tar xvf my1.tar -g /dev/null
test/
test/hosts

Restore day 2:

$ tar xvf my2.tar -g /dev/null
test/
tar: Deleting `test/hostname'

Check:

$ ls test
hosts services
$ tail -1 test/hosts
hi