MSYNC(2) BSD System Calls Manual MSYNC(2)NAMEmsync — synchronize a mapped region
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/types.h>
#include <sys/mman.h>
int
msync(void *addr, size_t len, int flags);
DESCRIPTION
The msync() system call writes any modified pages back to the filesystem
and updates the file modification time. If len is 0, all modified pages
within the region containing addr will be flushed; if len is non-zero,
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
RETURN VALUES
The msync() function returns the value 0 if successful; otherwise the
value -1 is returned and the global variable errno is set to indicate the
error.
ERRORSmsync() will fail if:
[EINVAL] addr is not a multiple of the hardware page size.
[EINVAL] len is too large or negative.
[EINVAL] flags was both MS_ASYNC and MS_INVALIDATE. Only one
of these flags is allowed.
[EIO] An I/O error occurred while writing to the file sys‐
tem.
SEE ALSOmadvise(2), mincore(2), mprotect(2), munmap(2)HISTORY
The msync() function first appeared in 4.4BSD.
BSD June 21, 1994 BSD
