'\"macro stdmacro
.if n .pH g2.sync @(#)sync	40.11 of 1/3/91
.\" Copyright 1991 UNIX System Laboratories, Inc.
.\" Copyright 1989, 1990 AT&T
.nr X
.if \nX=0 .ds x} sync 2 "" "\&"
.if \nX=1 .ds x} sync 2 ""
.if \nX=2 .ds x} sync 2 "" "\&"
.if \nX=3 .ds x} sync "" "" "\&"
.TH \*(x}
.SH NAME
\f4sync\f1 \- update super block
.SH SYNOPSIS
\f4#include <unistd.h>\f1
.PP
\f4void sync(void);\f1
.SH DESCRIPTION
\f4sync\fP
causes all information in
memory that should be on disk to be written out.
This includes modified super blocks,
modified i-nodes, and delayed block I/O.
.PP
It should be used by programs that examine a file system,
such as
\f4fsck\fP(1M),
\f4df\fP(1M),
etc.
It is mandatory before a re-boot.
.PP
The writing, although scheduled, is not necessarily
completed before \f4sync\fP returns.
The \f4fsync\fP system call completes the writing before it returns.
.SH "SEE ALSO"
\f4fsync\fP(2)