HP-UX Reference (11i v2 07/12) - 2 System Calls (vol 5)

fsync(2) fsync(2)

NAME

fsync(), fdatasync() - synchronize a ﬁle’s in-core and on-disk states

SYNOPSIS

#include <unistd.h>

int fsync(int fildes);

int fdatasync(int fildes);

DESCRIPTION

fsync() and fdatasync() cause 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() and fdatasync() apply to ordinary ﬁles, and apply to block special dev-

ices on systems which permit I/O to block special devices.

fsync() and fdatasync() should be used by programs that require a ﬁle to be in a known state, such

as when building a simple transaction facility.

fdatasync() causes all modiﬁed data and ﬁle attributes of ﬁldes required to retrieve the data to be writ-

ten to disk.

fsync() causes all modiﬁed data and all ﬁle attributes of ﬁldes (including access time, modiﬁcation time

and status change time) to be written to disk.

Together,

fsync() and fdatasync() constitute support for File Synchronization.

RETURN VALUE

fsync() and fdatasync() return 0 on success or −1 if an error occurs, and set errno

to indicate

the error.

ERRORS

fsync and fdatasync fail if any of the following conditions are encountered:

[EBADF] ﬁldes is not a valid descriptor.

[EINVAL] ﬁldes refers to a ﬁle type to which

fsync() or fdatasync() does not apply.

WARNINGS

The current implementation of these functions is inefﬁcient for large ﬁles.

AUTHOR

fsync() was developed by the the University of California, Berkeley and HP.