tar for backup

[Jeff Vian]

On Fri, 2004-07-09 at 04:15, Andrea Marin wrote:
> Hi all,
> 
> I try to make a backup whit the command tar.
> I make a simple script whit this line:
> 
> tar cvzf $BACKUP_DEST_DIR/$BACKUP_FILENAME.tar.gz $BACKUP_DIRS
> 
> where the $BACKUP_DEST_DIR/$BACKUP_FILENAME and $BACKUP_DIRS are my
> variables.
> Now I would like to make a more profit backup.
> 
> My variable $BACKUP_FILENAME contain a name pippo and when i make a
> second backup whit the same name the first archive are delete for write
> the new archive.
> I want that the tar program confront the two archive and write only one
> archive whit the files that was in the first archive more the difference
> that are whit the second, and if in the second archive there aren't some
> file the tar don't delete those file from the first archive.
> 
> Thanks Andrea
> 
man tar.

There are options to replace/update/add files that will do what you need
with a little judicious planning and script manipulation.

The output in this case would be to the original file so it can look at
what is there and choose what changes to make.