How to accidentally reboot a server
This is a little war story.
To start out, determine that you need to add more memory to one of your login servers. This requires taking it down, which requires getting all of its users to log off first. Then go through the following steps:
- Keep new logins off the system by changing your automated password
management system to give all non-staff accounts a login shell
that just prints out a 'this system is under maintenance, please
use another one' and then quits.
(Otherwise people will keep logging in to the server and you'll never, ever get a moment where there is no one on. Especially during working hours.)
- Mail all of the current users to ask them to log off.
- Get email from one user saying 'you can kill all of my processes
on the machine'.
- Do this in the obvious way. From an existing root session:
kill -1 -1
- Have all of your (staff) sessions to the machine suddenly disconnect. Get a sinking feeling.
Perhaps you can spot the mistake already. The mistake is that the
to the user did not actually work. The user had a locked login shell, so
su did was print a message and then dump me back into the root
shell. Then I ran the '
kill -1 -1' as root and of course it SIGHUP'd
all processes on the machine, effectively rebooting it.
(It didn't actually reboot and in fact enough stayed up that I could
ssh back in, which surprised me a little bit.)
I should have used '
/bin/su user -c "kill -1 -1"' or in fact one of
the ways we keep around to do 'run command as user no matter what their
shell is'. But I didn't take the time to do either of them.
(On the 'good' side, we got to immediately add more memory to that server.)
My Cinnamon desktop customizations
As I mentioned in the previous entry on my laptop environment, I'm now using a lightly customized Cinnamon desktop on Fedora 19. The major customizations have been to get back something equivalent to sshmenu and the Gnome 2 mini-commander applet. The results have been quite good; I feel as productive with my Cinnamon setup as I did with Gnome 2 on Fedora 14 (and many more things work on Fedora 19).
My mini-command replacement is that Cinnamon lets you add custom
keyboard shortcuts so I have F5 set to run a version of my custom
dmenu setup. This gives me convenient access
to ssh to other hosts (what I really care about)
as well as a bunch of other things. F5 is the same key as I use for this
on my desktop, although it is somewhat less convenient on the laptop
keyboard (time may change that).
To get an equivalent of sshmenu I use this launcher applet in the Cinnamon
panel. The launcher doesn't directly do SSH and it doesn't have submenus
(as far as I know), but you can create menu entries and specify the
command that they run and I already have a script to run SSH to a
host inside an
xterm. It's not as nice as
sshmenu but it'll do.
(There is a Cinnamon SSH applet but it didn't install when I tried it and it's not usefully customizable from what I understand. Sshmenu itself is unsuitable for a number of reasons, including that it appears to have been abandoned and doesn't actually work with Ruby 2.0.)
I've done some other less important Cinnamon customizations:
- F4 starts a (local)
xterm, partly because I haven't changed the Cinnamon panel's 'terminal' launcher away from running gnome-terminal.
- I'm using this Shutdown menu applet because I
find it more convenient than trying to find everything I want in
the main Cinnamon menu (and I don't like to be prompted).
- I have a shell script I run on session startup to do things like
set X resources for
xterm to gnome-terminal in general, but the one nice feature
g-t has (in a constrained laptop environment) is that it has a direct
way to open URLs in text. My current experiment with doing this with
xterm is to have F6 run a command that pulls out the current selection
and starts a browser on it if it looks URL-like (and otherwise just
start a browser on nothing in particular). This still leaves me actually
selecting the URL, which is more work on a laptop trackpad than it is on
(I would like to find a better replacement for
xterm someday but it's
hard. Everyone either adds features I don't care about instead of the
ones that I really would like or gets important things wrong. Often
it's both. Note that I'm very picky about how a terminal program should
behave and there are very few new features I actually want.)
Hopefully Cinnamon will stay stable for a few years so that I don't have to revisit this process for a while. Although I suppose I'm now basically okay as long as whatever desktop I settle in allows me to run a command in response to a function key, since dmenu is really what makes the environment work.
Sidebar: disabling cursor blinking in
gsettings set org.gnome.desktop.interface cursor-blink false
This probably has some global effect but I don't care any more.
(It also looks like gnome-terminal may still respect old settings stuffed in various corners, although who knows how and how you set which ones of them now on a new machine.)
While I'm writing this stuff down, the gsettings schema for what the standard terminal program is is org.gnome.desktop.default-applications.terminal. Your guess is as good as mine as to what programs respect this.