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RedHat 9 (Linux i386) - man page for sync (redhat section 2)

SYNC(2) 						     Linux Programmer's Manual							   SYNC(2)

NAME
sync - commit buffer cache to disk.
SYNOPSIS
#include <unistd.h> void sync(void);
DESCRIPTION
sync first commits inodes to buffers, and then buffers to disk.
CONFORMING TO
SVr4, SVID, X/OPEN, BSD 4.3
BUGS
According to the standard specification (e.g., SVID), sync() schedules the writes, but may return before the actual writing is done. How- ever, since version 1.3.20 Linux does actually wait. (This still does not guarantee data integrity: modern disks have large caches.)
NOTES
Since glibc 2.2.2 the Linux prototype is as listed above, following the various standards. In libc4, libc5, and glibc up to 2.2.1 it was "int sync(void)", and sync always returned 0.
SEE ALSO
bdflush(2), fsync(2), fdatasync(2), update(8), sync(8) Linux 2.4 2001-10-10 SYNC(2)