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.\"	from: @(#)msync.2	6.1 (Berkeley) 5/27/91
.\"	$Id: msync.2,v 1.2 1993/08/01 07:42:36 mycroft Exp $
.\"
.TH MSYNC 2 "May 27, 1991"
.UC 7
.SH NAME
msync \- synchronize a mapped region
.SH SYNOPSIS
.nf
msync(addr, len)
.B caddr_t addr;
.B int len;
.fi
.SH DESCRIPTION
.PP
The \fImsync\fP system call
writes any modified pages back to the filesystem and updates
the file modification time.
If \fIlen\fP is 0, all modified pages within the region containing \fIaddr\fP
will be flushed;
if \fIlen\fP is non-zero, only the pages containing \fIaddr\fP and \fIlen\fP
succeeding locations will be examined.
Any required synchronization of memory caches
will also take place at this time.
Filesystem operations on a file that is mapped for shared modifications
are unpredictable except after an \fImsync\fP.
.SH "SEE ALSO"
msync.2, munmap.2, mprotect.2, madvise.2, mincore.2