osf1 man page for msync

msync(2)							System Calls Manual							  msync(2)

NAME
       msync - Synchronizes a mapped file

SYNOPSIS
       #include <sys/mman.h>

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

       The following function declaration does not conform to current standards and is supported only for backward compatibility:

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

       int msync(
	       caddr_t addr,
	       size_t len,
	       int flags);

STANDARDS
       Interfaces documented on this reference page conform to industry standards as follows:

       msync(): XSH5.0

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

PARAMETERS
       Specifies  the  starting  address  of the region to be synchronized.  Specifies the length in bytes of the region to be synchronized.  This
       parameter must be a multiple of the page size as returned by sysconf(_SC_PAGE_SIZE).  If len is not a multiple of the page size as returned
       by sysconf(_SC_PAGE_SIZE), the length of the region will be rounded up to the next multiple of the page size.  Specifies one of the follow-
       ing symbolic constants defined in the sys/mman.h file: Specifies an asynchronous cache flush.  The msync() function returns after the  sys-
       tem  schedules  all  write  operations.	 Specifies a synchronous cache flush.  The msync() function returns after the system completes all
       write operations.  Specifies invalidating all cached pages.  New copies of the pages must be obtained from the file system  the	next  time
       they are referenced.

DESCRIPTION
       The  msync()  function  controls  the caching operations of a mapped file region.  The msync() function can be used to ensure that modified
       pages in the region are transferred to the file's underlying storage device.  (However, normal system activity can cause pages to be  writ-
       ten to a storage device, so there is no guarantee that a call to the msync() function is the only control over when pages are written.) You
       can also use the function to control the visibility of modifications with respect to file system operations.

       After a successful call to the msync() function with the flags parameter set to MS_SYNC, all previous modifications to  the  mapped  region
       are visible to processes using the read() function. Previous modifications to the file using the write() function might be lost.

       After a successful call to the msync() function with the flags parameter set to MS_INVALIDATE, all previous modifications to the file using
       the write( function are visible to the mapped region.  Previous direct modifications to the mapped region might be lost.

RETURN VALUES
       Upon successful completion, the msync() function returns 0 (zero).  Otherwise, the msync() function returns -1 and sets errno  to  indicate
       the error.

ERRORS
       The msync() function sets errno to the specified values for the following conditions:

       Some or all of the addresses in the range starting at addr and continuing for len bytes are locked, and MS_INVALIDATE is specified.  [Tru64
       UNIX]  The range [addr, addr + len) includes an invalid address.  The addr parameter is not a multiple of the  page  size  as  returned	by
       sysconf(_SC_PAGE_SIZE).	An I/O error occurred while reading from or writing to the file system.  The range specified by [addr, addr + len)
       is invalid for a process' address space, or the range specifies one or more unmapped pages.

RELATED INFORMATION
       Functions: fsync(2), mmap(2), read(2), write(2)

       Routines: sysconf(3)

       Standards: standards(5) delim off

																	  msync(2)