Backup to tar the updated files ONLY

[malleeblue]

In this post mdpalow wrote that it's possible to "copy updated files to another drive using tar".

I use tar to take daily backups of some of my files but when I run the below command it's still copying all the files to the tar again.

sudo tar uvpf /media/BACKUP-1/backupFLASHDRIVE.tar /media/FLASHDRIVE

Could you please tell me what I'm doing wrong and explain how, when my backup runs, I can get it to only copy the updated files?

[unutbu]

The tar command "tar uvpf" uses the update flag. According to
http://www.gnu.org/software/tar/manu...tar.html#SEC57

‘--update’ (‘-u’) is not suitable for performing backups for two reasons: it does not change directory content entries, and it lengthens the archive every time it is used.

To do incremental backups with tar, see
http://www.gnu.org/software/tar/manu...ups.html#SEC87
(in particular, section 5.2)

However, I wonder if a different tool such as rsync might be easier to use.
For example,

rsync -a /media/FLASHDRIVE/ /media/BACKUP-1

would copy all files from /media/FLASHDRIVE/ to /media/BACKUP-1.
One subsequent runs only files that have changed will get transferred.