fsync(2) [osf1 man page]
fsync(2) System Calls Manual fsync(2) NAME
fsync - Writes changes in a file to permanent storage SYNOPSIS
#include <unistd.h> int fsync ( int fildes ); STANDARDS
Interfaces documented on this reference page conform to industry standards as follows: fsync(): XPG4 Refer to the standards(5) reference page for more information about industry standards and associated tags. PARAMETERS
Specifies a valid open file descriptor. DESCRIPTION
The fsync function causes system buffers containing a file's modified data and attributes to be written to permanent storage. The fsync function does not return until the operation has been completed. The fsync function provides file integrity, ensuring that data and file attribute information in permanent storage is identical to data and file attribute information in the buffer. NOTES
The file identified by the fildes parameter must be open for writing when the fsync function is issued or the call will fail. RETURN VALUES
Upon successful completion, the fsync function returns a value of 0 (zero). If the fsync function fails, a value of -1 is returned and errno is set to indicate the error. If fsync fails, outstanding I/O operations are not guaranteed to have been completed. ERRORS
If the fsync function fails, errno may be set to one of the following values: [EBADF] The fildes parameter is not a valid file descriptor. [EINVAL] The fildes parameter does not refer to a file on which this operation is possible. If any queued I/O operations fail, the fsync function returns error conditions defined for the read and write functions. RELATED INFORMATION
Functions: aio_fsync(2), fdatasync(2), fcntl(2), open(2), read(2), sync(2), write(2) Standards: standards(5) delim off fsync(2)
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fsync(3C) Standard C Library Functions fsync(3C) NAME
fsync - synchronize changes to a file SYNOPSIS
#include <unistd.h> int fsync(int fildes); DESCRIPTION
The fsync() function moves all modified data and attributes of the file descriptor fildes to a storage device. When fsync() returns, all in-memory modified copies of buffers associated with fildes have been written to the physical medium. The fsync() function is different from sync(), which schedules disk I/O for all files but returns before the I/O completes. The fsync() function forces all outstanding data operations to synchronized file integrity completion (see fcntl.h(3HEAD) definition of O_SYNC.) The fsync() function forces all currently queued I/O operations associated with the file indicated by the file descriptor fildes to the synchronized I/O completion state. All I/O operations are completed as defined for synchronized I/O file integrity completion. RETURN VALUES
Upon successful completion, 0 is returned. Otherwise, -1 is returned and errno is set to indicate the error. If the fsync() function fails, outstanding I/O operations are not guaranteed to have been completed. ERRORS
The fsync() function will fail if: EBADF The fildes argument is not a valid file descriptor. EINTR A signal was caught during execution of the fsync() function. EIO An I/O error occurred while reading from or writing to the file system. ENOSPC There was no free space remaining on the device containing the file. ETIMEDOUT Remote connection timed out. This occurs when the file is on an NFS file system mounted with the soft option. See mount_nfs(1M). In the event that any of the queued I/O operations fail, fsync() returns the error conditions defined for read(2) and write(2). USAGE
The fsync() function should be used by applications that require that a file be in a known state. For example, an application that contains a simple transaction facility might use fsync() to ensure that all changes to a file or files caused by a given transaction were recorded on a storage medium. The manner in which the data reach the physical medium depends on both implementation and hardware. The fsync() function returns when notified by the device driver that the write has taken place. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |Async-Signal-Safe | +-----------------------------+-----------------------------+ SEE ALSO
mount_nfs(1M), read(2), sync(2), write(2), fcntl.h(3HEAD), fdatasync(3RT), attributes(5), standards(5) SunOS 5.10 24 Jul 2002 fsync(3C)