Вы можете попробовать:
#!/bin/bash
if [ ! -d $HOME/backup ]; then
mkdir $HOME/backup
fi
cd $HOME/folder
for i in *; do
if [ -d "$i" ]; then
tar -cf $HOME/backup/"$i".tar -T /dev/null #create an empty, uncompressed, archive
cd "$i"
ls -t | head -10 | while read file; do
tar -rf $HOME/backup/"$i".tar "$file" #append $file to archive
done
gzip $HOME/backup/"$i".tar # compress the archive
cd $OLDPWD
fi
done
echo "Backup copied in $HOME/backup/"
exit 0