rsync
networkingA fast, versatile remote (and local) file-copying tool that uses a delta-transfer algorithm to minimise data transferred.
Pronunciation
Correct
R-sink
/ˈɑːrsɪŋk/
The 'r' is spoken as the letter R, and 'sync' is pronounced as the word 'sync' (rhymes with 'link'). The rsync man page and project documentation confirm this.
Source: rsync.samba.org(official docs)