I've written a shell script to make incremental backups and have a question about flags to tar.

here's an exerpt. variables are set earlier in the script

echo "Saving files from web directory"
# this tars up my web directory into web.tar.gz tarball.
/bin/tar -czf $TMP$WEB_FILENAME --after-date=$LAST /var/www/htdocs

The script works fairly well, but the resulting archives contain a lot of empty folders in addition to the folders containing the files that have been changed since the last backup. What flag, if any could I add to this line to have the empty folders not be included in the archive.

Is there no answer? Or is it just that nobody knows?

check up the man/info pages .... tho I'm not sure if tar can exclude things.. might need a separate program for that

Are any of these what I need?

-G, --incremental
create/list/extract old GNU-format incremental backup

-g, --listed-incremental F
create/list/extract new GNU-format incremental backup
-i, --ignore-zeros
ignore blocks of zeros in archive (normally mean EOF)

-S, --sparse
handle sparse files efficiently

Here's my current script in case anybody wants to see it.

#
# inc-backup shell script for making incremental backups
#
# generation of ssh keys and tranferring them to the remote
# server prior to running the script is necessary
#

REM_USER="i7500"
REM_ADDR="192.168.1.109"
REMOTE_MACHINE=$REM_USER"@"$REM_ADDR

TMP="/tmp/"

TODAY=`date +%F`

if [ -f /tmp/lastbackup ]; then
LAST=`cat /tmp/lastbackup`
else
LAST=$TODAY
fi

WEB_FILENAME="inc-"$TODAY"-web.tar.gz"

HOME_FILENAME="inc-"$TODAY"-home.tar.gz"

echo "Saving files from web directory"
# this tars up my web directory into web.tar.gz tarball.
/bin/tar -czf $TMP$WEB_FILENAME --after-date=$LAST /var/www/htdocs

echo "Transferring web files to backup server"
# This sends the tarball to the remote directory
cat $TMP$WEB_FILENAME | ssh $REMOTE_MACHINE "cd backup; cat > $WEB_FILENAME"

echo "Removing web backup files"
# remove web backup file from temp directory
rm $TMP$WEB_FILENAME

echo "Saving files from home directory"
# this tars up my home directory into myhome.tar.gz tarball.
/bin/tar -czf $TMP$HOME_FILENAME --after-date=$LAST /home/jeff

echo "Transferring home files to backup server"
# This sends the tarball to the remote directory
cat $TMP$HOME_FILENAME | ssh $REMOTE_MACHINE "cd backup; cat > $HOME_FILENAME"

echo "Removing home backup files"
# remove home backup file from temp directory
rm $TMP$HOME_FILENAME

echo $TODAY > /tmp/lastbackup

exit;