On Sun, Jun 14, 2020 at 6:19 PM Pete Biggs <pete at biggs.org.uk> wrote: > > > I'm quite sure that in original Berkeley Unix, as on the VAX 11/780, halt > > was an immediate halt of the CPU without any process cleanup or file > system > > umounting or anything. Early SunOS (pre-Solaris) was like this, too. > > > The SunOS 4.1.2 man page for halt says > > NAME > halt - stop the processor > SYNOPSIS > /usr/etc/halt [ -oqy ] > DESCRIPTION > halt writes out any information pending to the disks and then > stops the processor. > halt normally logs the system shutdown to the system log > daemon, syslogd(8), and places a shutdown record in the > login accounting file Ivar/admlwtmp. > These actions are inhibited if the -0 or -q options are present. > > The BSD 4.3 (that ran on VAXen) man pages say largely similar things: > > > https://www.freebsd.org/cgi/man.cgi?query=halt&apropos=0&sektion=0&manpath=4.3BSD+Reno&arch=default&format=html > > ok, so it does a sync then hard halts, but it doesn't gracefully exit services, or unmount file systems. -- -john r pierce recycling used bits in santa cruz