Macintosh Terminal Pocket Guide

Name

sync — stdin  stdout  - file  -- opt  --help  --version

Synopsis

sync

The sync command flushes all disk caches to disk. OS X usually buffers reads, writes, inode changes, and other disk-related activity in memory. sync writes the changes to disk. Normally, you don’t need to run this command, but if, say, you’re about to do something risky that might crash your machine, running sync immediately beforehand will make sure any pending disk writes are completed first.