NAME

fsync − synchronize a file’s in-core state with its state on disk

SYNOPSIS

int fsync(fildes)
int fildes;

DESCRIPTION

Fsync causes all modified data and attributes of fildes to be moved to a permanent storage device.  This normally results in all in-core modified copies of buffers for the associated file to be written to a disk.  Fsync applies to ordinary files, and applies to block special devices on systems which permit I/O to block special devices. 

Fsync should be used by programs which require a file to be in a known state; for example in building a simple transaction facility. 

ERRORS

Fsync will fail if one of the following conditions is true and errno will be set accordingly:

­[EBADF] Fildes is not a valid descriptor. 

­[EINVAL] Fildes refers to a file type to which fsync does not apply. 

RETURN VALUE

A 0 value is returned on success.  A −1 value indicates an error. 

BUGS

The current implementation of this call is expensive for large files. 

AUTHOR

Fsync was developed by the Hewlett-Packard Company, and the University of California, Berkeley California, Computer Science Division, Department of Electrical Engineering and Computer Science. 

SEE ALSO

fcntl(2), fcntl(5), open(2), select(2), sync(2), sync(1M). 

Hewlett-Packard Company  —  Version B.1,  May 11, 2021