[somesortofsystm]

"One sync tells the system to flush all i/o buffers, the second one serves to ensure the buffers are sync'ed, and the third is useful in case slow-quitting processes meanwhile even still have things to flush before letting go of a node, and then of course .. ;reboot .. "

Yeah, but it also means, if done in rapid succession (i.e. one shell cmd "sync;sync;sync", it can tell the machine on the other end of the i/o to do 'special' operations, such as rewind tape, settle card tray intake, etc.

Long-forgotten aspects of operation which neverless fit in the 'class' of action, where data is settled and made safe.