Command help?

[Rick Stevens]

Bradley wrote:
> Aldo Foot wrote:
>> On Wed, Sep 24, 2008 at 12:58 PM, Bradley <pursley001 at comcast.net> wrote:
>>   
>>> Okay,
>>>
>>>    I am starting to do some more advanced automated maintenance on my
>>> system but can't find a nifty way to do something and was wondering if
>>> anyone out there can help me with this.  I am configuring my system to
>>> do an automated backup of all my data (2 to 4 hours per week) but need
>>> it to do certain things to protect the process.
>>>
>>>    For an unattended process, I need to know how to:
>>>
>>>   1. Force all users currently logged on to be logged off (preferably
>>>      with at least a 5 minute notice).
>>>   2. Prevent anyone from logging on.
>>>   3. Prevent the system from being shut down or rebooted.
>>>   4. Shut down the X server (speeds up processing time considerably).
>>>   5. After finished to restart X server and allow shutdown and logins.
>>>
>>>    If anyone knows any commands to do at least some of these, I would
>>> appreciate knowing how.  The part about shutting down the X server is
>>> optional but would be nice but not allowing anyone to be logged in and
>>> preventing system shut down is necessary.
>>>
>>> Bradley
>>>     
>> My 0.02 cents.
>>
>> start by doing man on login, nologin, shutdown, killall etc...
>>
>> /etc/nologin -- prevents user logins
>>
>> shutdown -k     Don't really shutdown; only send the warning messages
>> to everybody.
>>
>> killall      -u, --user
>>               Kill  only  processes  the  specified  user owns.
>> Command names are
>>               optional.
>>
>> ~af
> Thanks for the input but, unfortunately, this doesn't give the results
> that I need.
> 
>  I gave up and configured one of the run levels for doing the needed
> tasks and have the system reboot into that run level where it does what
> I need it to and then reboots the system back to the normal run level. 
> Not a pretty arrangement but it seems to work.  While in the special run
> level, it does not activate any unnecessary services (network, servers,
> Xserver, etc.) and does not allow any user logins.  This turned out to
> be simpler and cleaner to set up than what I had previously considered.

Here's a script that might do what you want:
--------------------------- CUT HERE -----------------------------------
#!/bin/bash
# Send a message to all users...
wall The system will be shutting down in five minutes.  Please log off now!

# Prevent new logins...
echo "Logins temporarily disabled" >/etc/nologin

# Wait 5 minutes...
sleep 300

# Log off all users...
for USER in `who | cut -d " " -f 1`; do if [ $USER != "root" ]; then 
killall -u $USER; fi; done

# Shut down X by going to run level 3...
telinit 3

echo "System quiescent...ready for updates"
echo -n "Press the ENTER key when you want to return to normal: "
read USERINPUT

# Re-enable logins...
rm -f /etc/nologin

# Restart X...
telinit 5
telinit Q

echo "System returned to normal"
exit 0
--------------------------- CUT HERE -----------------------------------

This script must be run as root in a virtual console (ALT-F1, ALT-F2,
etc.--NOT an xterm).  It may break at the "telinit 3" bit (I think it'll
continue to run).  I've not tested it, but there's nothing particularly
dangerous about it.

Note that there's no way to prevent reboots or shutdowns.  Normally,
CTRL-ALT-DEL will do a soft shutdown/reboot.  You can change that to a
hard reboot (no syncing of dirty disk buffers, etc.), but you can't stop
it.
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- Rick Stevens, Systems Engineer                      ricks at nerd.com -
- AIM/Skype: therps2        ICQ: 22643734            Yahoo: origrps2 -
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-              After all, 31 Oct is the same as 25 Dec!              -
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