May 31, 1993 SYNC 8

### NAME

sync - force completion of pending disk writes (flush cache)

### SYNOPSIS

sync

### DESCRIPTION

The sync program can be called to ensure that all disk writes have been completed before the processor is halted in a way not suitably done by reboot(8) or halt(8). Generally, it is preferable to use reboot(8) or halt(8) to shut down the system, as they may perform additional actions such as resynchronizing the hardware clock and flushing internal caches before performing a final .

The sync program simply invokes the sync(2) system call.

### SEE ALSO

fsync(2), sync(2), halt(8), reboot(8)

### HISTORY

A sync command appeared in Version 6 `AT&T UNIX`.