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Command: sync | Section: 2 | Source: FreeBSD | File: sync.2.gz
SYNC(2) FreeBSD System Calls Manual SYNC(2)
NAME
sync - schedule file system updates
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <unistd.h>
void
sync(void);
DESCRIPTION
The sync() system call forces a write of dirty (modified) buffers in the
block buffer cache out to disk. The kernel keeps this information in
core to reduce the number of disk I/O transfers required by the system.
As information in the cache is lost after a system crash, a sync() system
call is issued frequently by the kernel process syncer(4) (about every 30
seconds).
The fsync(2) system call may be used to synchronize individual file
descriptor attributes.
SEE ALSO
fsync(2), syncer(4), sync(8)
HISTORY
The sync() function appeared in Version 3 AT&T UNIX.
BUGS
The sync() system call may return before the buffers are completely
flushed.
FreeBSD 14.1-RELEASE-p8 December 1, 2017 FreeBSD 14.1-RELEASE-p8