Note: This is an RHCSA 7 exam objective.
Switch on a physical server or a virtual machine (in this case, type: # virsh start vm).
Connect to the console.
To reboot the system, choose one command among these:
# reboot # systemctl reboot # shutdown -r now # init 6 # telinit 6
To shutdown the system, choose one command among these:
# halt # systemctl halt # shutdown -h now # init 0 # telinit 0
To switch off the system, choose one command among these:
# poweroff # systemctl poweroff
To suspend the system, type:
# systemctl suspend
To put the system into hibernation, type:
# systemctl hibernate
To put the system into hibernation and suspend it, type:
# systemctl hybrid-sleep
Bob Cromwell provides some very interesting pages about Linux kernel details and the Linux boot process.
These also will work:
telinit 0 #shutdown
telinit 6 #reboot
So I have used the systemctl halt command, it halted the system. Now, how do I get back to normal operations from here ? (I am on a virtual machine.)
It depends on the virtualization software that you are using.
If you use KVM, execute virsh start vm.
If you use VirtualBox, use the VirtualBox interface to start the vm.
Right now I am using virtualbox. What I really wanted to know is what I would do if it were a physical server. Is there a keystroke combination (like ctrl+alt+del) which will take a halted system to active mode, or will I have to yank the power cord and start the machine again?
Sorry, I edited your question because I didn’t find the first part of it very clear.
Concerning a keystroke combination to halt a physical system, I don’t think there is. You can enable it but it’s not by default.
Sorry for not making the question more clear.
Question 1: I have a system which is in a halt state (by using systemctl halt command).
Now, I want to go back to normal mode to work on the server. How do I do that?
Case 1: virtual server
Case 2: physical server.
In the case 1, as you suggested using virtualbox interface but I can not start a halted vm, because it is already in running state.
As I’m not regularly using VirtualBox, I leave someone else answer for the case 1.
Concerning the case 2, physical server, you can’t do anything except if you’ve got an out-of-band management system (iLO, DRAC, etc) as Lisenet said. An out-of-band management system is a way to remotely switch off/switch on a server.
If you VirtualBox VM is halted, then try these:
vboxmanage controlvm $vm_name poweroff
vboxmanage startvm $vm_name
Are you talking about out-of-band management (aka lights-out management)? In such case you want iLO or DRAC.
My two cents …
shutdown -r is better because it warns the other users and you can put a time to plan the reboot and a message.
reboot / init 6 to go fast but often if the server is not in production.
Rq : I think hibernation is not a good idea for server… it’s better to keep it for Linux Desktop to avoid to use too much swap when you have more than 64G RAM for instance.