synchronization

• http://www.csync.org
• http://www.cis.upenn.edu/~bcpierce/unison/
• https://balaskas.gr/blog/?page=PIrsyncD
• http://duplicity.nongnu.org/
• http://fsvs.tigris.org/purpose.html

• http://www.dirvish.org/
• http://www.rsnapshot.org
• http://www.nongnu.org/rdiff-backup/