NAME

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

SYNOPSIS

fsync(fildes)
int fildes;

HP−UX COMPATABILITY

Level: Basic Calls: HP-UX/RUN ONLY
Real Time extensions: HP-UX/STANDARD - Real Time

Origin: UCB and HP

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. 

WARNING

If the process has multiple file descriptors open on a file and the file descritpors have asynchronous writes pending, then the process cannot be guaranteed that the buffers associated with these writes will be flushed by the fsync(2). The process must wait until all of the writes have completed before performing an fsync(2) call.

BUGS

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

SEE ALSO

fcntl(2), fcntl(7), open(2), select(2), sync(2), sync(8). 

Hewlett-Packard  —  last mod. May 11, 2021