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From"Eric S. Mountain" <>
SubjectRe: Eject, Rebooting, Shortcuts, kernel bloat
DateSun, 31 Mar 1996 21:11:06 +0100 (BST)
Laszlo Vecsey ecrivit:
> Is there a safe way to reboot the system, making absolutely sure that the
> file systems get unmounted before the system is restarted? I always have
> one partition that needs to be re-e2fscked each time on startup, probably
> because the processes that were using it were not terminated properly
> during shutdown and the filesystem wasn't unmounted and marked as clean.

This is a vagary I have encountered before: check out the Tips-HOWTO:
[ Quote from Tips-HOWTO ]
2.4. How to avoid fscks caused by "device busy" at reboot time. Jon
Tombs, jon@gtex02.us.es

If you often get device busy errors on shutdown that leave the
filesystem in need of an fsck upon reboot, here is a simple fix:

To /etc/brc or /sbin/brc, add the line

mount -o remount,ro /mount.dir

for all your mounted filesystems except /, before the call to umount
-a. This means if, for some reason, shutdown fails to kill all pro-
cesses and umount the disks they will still be clean on reboot. Saves
a lot of time at reboot for me
[ End quote ]

> And why is it that certain processes can go dead and not even kill -9 can
> remove them? How about having a ctrl-scroll-lock option that would list

These are called zombie processes. They are already dead, so you
can't kill them. I think they occupy zero-memory so apart from an
ugly entry in your ps -aux they won't do much harm. See the
comp.unix.shell FAQ "How do I get rid of zombie processes that
persevere?" for a discussion on this.

> all the processes and allow you to move up and down with a scrollbar,
> highlight the process you want (giving status information) and zap it if
> need be. Also, is it possible to have a process running that would NOT be
> listed with ps -x? I've heard it could be done. I would feel much better
> if the kernel could tell me exactly which processes are running, and give
> me the ability to zap or -SIGHUP them with ease.

ps -ax gives you a complete listing. No need to bloat the kernel with
this kind of work.

Also, you mean you want to give anyone the ability to kill any
process!?

> I don't see any security risk with having this kind of option freely
> available through a hotkey (i.e., even if root isn't logged in on a VC)

I see you _are_ serious. Wow.

> because anybody can hit ctrl-alt-del and insert a bootdisk and get full

Not if you disable booting from A: in the CMOS and put a password on
the CMOS setup. (OK, so they can open the box, short the CMOS
battery... ;)

> access. Actually, maybe we need a compile option to remove ctrl-alt-del

No need for a compile-option: edit your inittab file to disable CAD:
you want to comment-out the following:

# What to do when CTRL-ALT-DEL is pressed.
ca::ctrlaltdel:/sbin/shutdown -t1 -r now

:E
--
Eric S. Mountain - eric@minouche.demon.co.uk

No matter what occurs, someone believes it happened according to his pet theory


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