If you need to archive only the recently modified files you can use this simple syntax of the ‘tar’ command:
tar czf target-filename -N “8 hours ago” source-directory
The ‘-N’ flag (newer) accepts standard GNU relative date formate like “8 hours ago”, “1 day ago” and “-1 month” aswell
The ‘tar’ archive preserves the directory tree with all subfolders, making this command quite useful for easy file system incremental backups.
An example use of the command to backup your web files modified during the last day, will look like:
tar czf /var/backup/archive.tar.gz -N “1 day ago” /var/www