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Command: sync | Section: 2 | Source: OpenBSD | File: sync.2
SYNC(2) FreeBSD System Calls Manual SYNC(2)
NAME
sync - synchronize disk block in-core status with that on disk
SYNOPSIS
#include <unistd.h>
void
sync(void);
DESCRIPTION
The sync() function 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() call
is issued frequently by the in-kernel process update (about every 30
seconds).
The function fsync(2) may be used to synchronize individual file
descriptor attributes.
SEE ALSO
fsync(2), sync(8)
STANDARDS
The sync() function conforms to IEEE Std 1003.1-2008 ("POSIX.1").
HISTORY
A sync() function appeared in Version 2 AT&T UNIX.
BUGS
sync() may return before the buffers are completely flushed.
FreeBSD 14.1-RELEASE-p8 March 31, 2022 FreeBSD 14.1-RELEASE-p8