Traditional way of rebooting the system
# shutdown –[h/r] [now/30] [ which mean halt or reboot, now or
after 30 minutes
# shutdown –h now
Where –h is halt or r for reboot.
Now is time. Or you can specify after 30 minutes
On Redhat 7 based systems, runlevels are replaces by system
targets and managed by systemctl
#
systemctl halt
#
systemctl reboot
#
systemctl --nowall poweroff [no
message is sent to the terminal]
Boot systems into different targets manually
Run
level equivalent to system targets on RHEL7 based systems.
Runlevel
|
Target Units
|
Description
|
0
|
runlevel0.target, poweroff.target
|
Shut
down and power off the system.
|
1
|
runlevel1.target, rescue.target
|
Takes you to a rescue shell.
|
2
|
runlevel2.target, multi-user.target
|
Brings system to non-graphical multi-user system.
|
3
|
runlevel3.target, multi-user.target
|
Brings system to non-graphical multi-user system.
|
4
|
runlevel4.target, multi-user.target
|
Brings system to non-graphical multi-user system.
|
5
|
runlevel5.target, graphical.target
|
Brings system to a graphical multi-user system mode
|
6
|
runlevel6.target, reboot.target
|
Shut
down and reboots the system.
|
Check the
default target level
# systemctl
get-default
Set to a
different target level called multiuser system
# systemctl
set-default multi-user.target
Change the
default target to graphical.gar for GUI based login
# systemctl
set-default graphical.target
To switch
to non-GUI based target rightaway
# systemctl
isolate multi-user.target
Change
system to emergency target immediately
# systemctl
rescue/emergency
systemctl
rescue/emergency
You
can run systemctl on remote system as well
#
systemclt –H root@remove-host statys httpd
How to recover root password if you forgot
a. Reboot
your system whatever way available to you such as pressing power button or
login through the console.
b. On
splash menu where timer runs, press any key to stop the timer.
c. Press
e to edit the highlighted grub boot loader menu
d. Go
to the line linux16 and go to the end of the line. The best way is to press
CTRL+E key
e. At
the end of the line, type init=/bin/sh or type rd.break
f. Press
CTRL-X to boot the system, and you’ll be at the prompt.
g. Now,
system is mounted readonly, remount with read/write option
#
mount -o remount,rw /
#
chroot /sysimage
#
touch /.autorelebel
h. Press
CTRL+D
i. And
reboot the system using reboot at the prompt
j. #
reboot
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