Linux Administration-Shutdown problems

**pongsu** · 09-29-2003

hello,

1.Why the system must never be switched off without first shutting it down?

2.How can we shutdown the system using ‘init’? What is the command line for this to happen

3.What are the changes to be made to boot the system without network services being activated.

4.What is the relationship between the scripts kept in ‘/etc/rc.d’ and the run-levels?

Thanks

__________________
regards
pongsu

**andutt** · 09-29-2003

The quiestion Nr1 i dont understand...Of course the system is not turned of if you dont execute the shutdown command.

To see how the initcommand and structures are working see man init. But here is a short brief how the runlevels are working in redhat.

Code:

# Default runlevel. The runlevels used by RHS are&#58;
#   0 - halt &#40;Do NOT set initdefault to this&#41;
#   1 - Single user mode
#   2 - Multiuser, without NFS &#40;The same as 3, if you do not have networking&#41;
#   3 - Full multiuser mode
#   4 - unused
#   5 - X11
#   6 - reboot &#40;Do NOT set initdefault to this&#41;

The /etc/inittab are controling which defaultrunlevels to use and which programs to be started by init. Depending on which runlevel to goto init are using /etc/rc<runlevel>.d/* scripts to shutdown and start services.

With

Code:

chkconfig --list

You can see which services that are starting i resp runlevel. To disable and enable services use this command

Code:

chkconfig --level 0123456 network off to turn off and chkconfig --level 3 network on to turn on

**sykkn** · 09-29-2003

Originally Posted by pongsu

1.Why the system must never be switched off without first shutting it down?

You should never just power off a system without using the shutdown, reboot, init 0, or init 6 command because you could potentially lose important data.

From my understanding ... when you save a change to a text file the change is not immediately written to disk. The change is cached ( buffered ) so that they can be written later when the system has more available resources.

**genlee** · 09-29-2003

Sounds like somebodies homework questions.

**andutt** · 09-30-2003

Yeah Genlee now that you saying it, it seems obvious....

**Mzzbizzsnatch** · 10-06-2003

Originally Posted by pongsu

hello,

2.How can we shutdown the system using ‘init’? What is the command line for this to happen?

Answer:

"man shutdown"

You'll want to read up on this. Pretty short read actually.

Example below: (read man shutdown first though)

Code:

shutdown -ah now

**Allblack** · 10-06-2003

I never used to get homework like that. Probably because I left school before Linux was released

**bpark** · 10-06-2003

So.. shutdown before poweroff... well the theory certainly makes sense.

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