fancy compressing managing checksumming deduplicating hard-linking cp -ua

 Copies directory hierarchies recursively into another location,
 by date (e.g. /home/ => /var/bkup/2002.12.13_04.27.56/).
 Permissions are preserved, so users with access to the backup
 directory can recover their files themselves.
 .
 File comparisons are done with MD5 checksums, so no changes go
 unnoticed.
 .
 Hard-links unchanged backuped files to old versions and
 identical files within the backuped tree.
 .
 Compresses large files (that don't match exclusion patterns).
 .
 Manages backups and removes old ones.