Hi, to...@tuxteam.de wrote: > > While I've read about issuing sync *twice* with the explanation > > that sysadmins are a supersticious bunch
Polyna-Maude Racicot-Summerside wrote: > I'm really asking why do it 3 time. > In case it came back to the prompt *before* finishing to do it's job ? I dimly remember that it was part of the shutdown procedure of one of the earliest Unix machines which i met. IBM RT, Apollo DN3000, microVAX ... ? The shutdown spell was something like sync ; sync ; halt Googling "sync halt" leads me to an interesting theory at https://bsdimp.blogspot.com/2020/07/when-unix-learned-to-reboot2.html According to section "That sync; sync; sync Thing..." two bugs of early systems' sync existed (one explored by the blog's author, one as rumor): 1: The sync system call returned without waiting. Workaround: Keep the human operator busy while the machine is still not done with flushing buffers. E.g. prescribe to type three lines of "sync" before typing "halt". 2: Only the first sync call returned early, whereas the second sync properly blocked until flushing was done. That seems to be the origin of my memory. Have a nice day :) Thomas
