sync (2)

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(The comments found at the beginning of the groff file "man2/sync.2freebsd".)

NAME

sync - schedule file system updates

LIBRARY

Lb libc

SYNOPSIS

In unistd.h Ft void Fn sync void

DESCRIPTION

The Fn sync system call forces a write of dirty (modified) buffers in the block buffer cache out to disk. The kernel keeps this information in core to reduce the number of disk I/O transfers required by the system. As information in the cache is lost after a system crash, a Fn sync system call is issued frequently by the user process syncer(4) (about every 30 seconds).

The fsync(2) system call may be used to synchronize individual file descriptor attributes.

SEE ALSO

fsync(2), syncer(4), sync(8)

HISTORY

The Fn sync function appeared in AT&T System v6 .

BUGS

The Fn sync system call may return before the buffers are completely flushed.