ADC Home > Reference Library > Reference > Mac OS X > Mac OS X Man Pages

 

This document is a Mac OS X manual page. Manual pages are a command-line technology for providing documentation. You can view these manual pages locally using the man(1) command. These manual pages come from many different sources, and thus, have a variety of writing styles.

This manual page is associated with the Mac OS X developer tools. The software or headers described may not be present on your Mac OS X installation until you install the developer tools package. This package is available on your Mac OS X installation DVD, and the latest versions can be downloaded from developer.apple.com.

For more information about the manual page format, see the manual page for manpages(5).



MSYNC(2)                    BSD System Calls Manual                   MSYNC(2)

NAME
     msync -- synchronize a mapped region

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/mman.h>

     int
     msync(void *addr, size_t len, int flags);

DESCRIPTION
     The msync() system call writes modified whole pages back to the filesystem and updates the file modifi-cation modification
     cation time.  Only those pages containing addr and len-1 succeeding locations will be examined.

     The flags argument may be specified as follows:

     MS_ASYNC        Return immediately
     MS_SYNC         Perform synchronous writes
     MS_INVALIDATE   Invalidate all cached data

     The MS_ASYNC flag is not permitted to be combined with other flags.

RETURN VALUES
     If any errors occur, -1 is returned and errno is set to indicate the error.  Otherwise, a 0 value is
     returned.

ERRORS
     msync() will fail if:

     [EBUSY]            Some of the specified addresses are locked and MS_INVALIDATE is specified.

     [EINVAL]           addr is not a multiple of the hardware page size.

     [EINVAL]           len is too large, or less than 1.

     [EINVAL]           flags is invalid (e.g., it combines MS_ASYNC with another flag, which is not permit-ted). permitted).
                        ted).

     [EIO]              An I/O error occurs while writing to the file system.

     [ENOMEM]           The specified address range is outside of the address range of the process or
                        includes an unmapped page.

LEGACY SYNOPSIS
     #include <sys/types.h>
     #include <sys/mman.h>

     The include file <sys/types.h> is necessary.

SEE ALSO
     madvise(2), mincore(2), mprotect(2), munmap(2), compat(5)

HISTORY
     The msync() function first appeared in 4.4BSD.

BSD                              June 21, 1994                             BSD

Did this document help you?
Yes: Tell us what works for you.
It’s good, but: Report typos, inaccuracies, and so forth.
It wasn’t helpful: Tell us what would have helped.