How can I logout users when reboot/halt over ssh, but so that their .bash_history is saved?

Question

When I reboot my server over SSH, the session just hangs instead of nicely logging me out, so that I can continue to use the current terminal. I tried the following to fix this: https://bbs.archlinux.org/viewtopic.php?id=50089 But then my bash history isn't saved before rebooting.

Is there a way to nicely log out all users (so that their bash history is saved) before a reboot/halt command? i.e. save bash history and end user sessions before reboot/halt?

OS: Ubuntu Server 11.04

Answer 1

You need to execute something like history -ain each user session. I can't think of a "nice" way to do this but using PROMPT_COMMAND in bash would work, PROMPT_COMMAND is an env variable for a command that is execute every time bash returns to a prompt, i.e. it automatically flushes the history to .bash_history on each command execute. Works but probably not the best solution. Put this in the .bashrc or in a profile.d file (if you are on profile.d compatible distro).

export PROMPT_COMMAND='history -a'

Answer 2

I found a solution:

I simply needed to use "killall -u" instead of the "skill -KILL -u". :) As indicated here: http://www.cyberciti.biz/tips/howto-linux-kill-and-logout-users.html , the command "skill" seems to be obsolete and others like pkill and killall should be used instead. pkill didn't do what I want, but killall did. :)

So here's the full solution:

1) Create a script /etc/init.d/killusers containing the following:

#!/bin/bash
#
# chkconfig: 35 90 12
# description: Foo server
#

# Get function from functions library
#. /etc/init.d/functions
. /lib/lsb/init-functions

# Start the service FOO
start() {
        #initlog -c "echo -n Starting FOO server: "
        #who | cut -d " " -f1 | uniq | xargs killall -u
        #who | cut -d " " -f1 | uniq | xargs skill -KILL -u
        #success $"FOO server startup"
        echo "Do nothing"
}

# Restart the service FOO
stop() {
        #initlog -c "echo -n Stopping FOO server: "
        who | cut -d " " -f1 | uniq | xargs killall -u
        #who | cut -d " " -f1 | uniq | xargs skill -KILL -u
        #who | cut -d " " -f1 | uniq | xargs pkill -STOP -u
}

### main logic ###
case "$1" in
  start)
        start
        ;;
  stop)
        stop
        ;;
  status)
        status FOO
        ;;
  restart|reload|condrestart)
        stop
        start
        ;;
  *)
        echo $"Usage: $0 {start|stop|restart|reload|status}"
        exit 1
esac

exit 0

( script based on http://www.cyberciti.biz/tips/linux-write-sys-v-init-script-to-start-stop-service.html )

2) Make it executable:

sudo chmod +x /etc/init.d/killusers

3) Add it to the shutdown scripts:

sudo update-rc.d killusers defaults

Note 1: I think runlevel 6 should be enough, but I went for defaults just to be sure. The script could probably also only contain the kill command if it is just run during shutdown.

Note 2: To save the bash history immediately, you can use (thanks to HampusLi):

history -a

So you could also just run:

history -a && sudo reboot

But I wanted it to work for any user and without having to create an alias, script or similar.