Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help 
FSYNC(2)		       System Calls Manual			FSYNC(2)

NAME
     fdatasync, fsync -- synchronise changes to a file

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <unistd.h>

     int
     fdatasync(int fd);

     int
     fsync(int fd);

DESCRIPTION
     The fsync() system call causes all modified data and attributes of the file
     referenced by the file descriptor fd to be moved to a permanent storage de-
     vice.   This normally results in all in-core modified copies of buffers for
     the associated file to be written to a disk.

     The fdatasync() system call causes all modified data of fd to be moved to a
     permanent storage device.	Unlike fsync(), the system call does not guaran-
     tee that file attributes or metadata necessary to access the file are  com-
     mitted to the permanent storage.

     The  fsync()  system call should be used by programs that require a file to
     be in a known state, for example, in building a simple  transaction  facil-
     ity.   If	the  file metadata has already been committed, using fdatasync()
     can be more efficient than fsync().

     Both fdatasync() and fsync() calls are cancellation points.

RETURN VALUES
     The fsync() function returns the  value  0  if  successful;  otherwise  the
     value  -1	is returned and the global variable errno is set to indicate the
     error.

ERRORS
     The fsync() and fdatasync() calls fail if:

     [EBADF]		The fd argument is not a valid descriptor.

     [EINVAL]		The fd argument refers to a socket, not to a file.

     [EIO]		An I/O error occurred while reading from or  writing  to
			the file system.

     [EINTEGRITY]	Corrupted  data was detected while reading from the file
			system.

SEE ALSO
     fsync(1), sync(2), syncer(4), sync(8)

HISTORY
     The fsync() system call appeared in 4.2BSD.  The  fdatasync()  system  call
     appeared in FreeBSD 11.1.

BUGS
     The  fdatasync()  system  call  currently	does not guarantee that enqueued
     aio(4) requests for the file referenced by  fd  are  completed  before  the
     syscall returns.

FreeBSD ports 15.1		 March 30, 2020 			FSYNC(2)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=fsync&sektion=2&manpath=FreeBSD+15.1-RELEASE+and+Ports>

home | help