sync - schedule file system updates
The sync() function shall cause all information in memory that updates file systems to be scheduled for writing out to all file systems.
The writing, although scheduled, is not necessarily complete upon return from sync().
The sync() function shall not return a value.
No errors are defined.
fsync(), the Base Definitions volume of IEEE Std 1003.1-2001, <unistd.h>
First released in Issue 4, Version 2.
Moved from X/OPEN UNIX extension to BASE.