fsync(2)fsync(2)Namefsync - synchronize a file's in-core state with that on disk
The system call causes all modified data and attributes of fd to be
moved to a permanent storage device. This results in all in-core modi‐
fied copies of buffers for the associated file to be written to a disk.
The call should be used by programs that require a file to be in a
known state, for example, in building a simple transaction facility.
A 0 value is returned on success. A -1 value indicates an error.
The call fails under the following conditions:
[EBADF] The fd argument is not a valid descriptor.
[EINVAL] The fd argument refers to a socket.
[EIO] An I/O error occurred while reading from or writing to
the file system.
[EINTR] The function was interrupted by a signal.
If an error occurs on an asynchronous write over NFS, the error cannot
always be returned from a system call. The error code is returned on
or The following are NFS-only error messages:
[EACCESS] The requested address is protected, and the current user
has inadequate permission to access it.
[ENOSPC] There is no free space remaining on the file system con‐
taining the file.
[EDQUOT] The user's quota of disk blocks on the file system con‐
taining the file has been exhausted.
[EROFS] The file is on a read-only file system.
[ESTALE] The fd argument is invalid because the file referred to
by that file handle no longer exists or has been
[ETIMEDOUT] A write operation failed because the server did not
properly respond after a period of time that is depen‐
dent on the options.
See Alsosync(1), close(2), sync(2), write(2), update(8)fsync(2)