Background: my computer (a rusty oldtimer) has a nice "feature": sometimes when I plug in my mp3-player it just turns off as if you had pushed the on/off switch. That's not the problem though, it occurs rarely enough so that I can live with it.

But I would be glad to be able to flush all the devices (especially the hard drives) before plugging in the mp3-player so that if the computer turns itself off, no data (or as little as possible) gets lost that was only there in the write cache at the time.

From what my Linux writes on the screen when it gets shut down ("flushing all devices" if I remember right) it seems it can do it. But can I manually force it?