Reset CentOS 7 root password through Single User Mode
While i was learning centos i used to install os on virtual machines and give passwords that i feel like easy to remember and hard to forget. But trust me if i am opening these machines after a three or four days gap, it would be easy for me to create a new virtual machine and install from scratch....
But there is a method to reset the root password for CentOS. Actually this method is applicable for all linux distributions with small changes in parameters to access single user mode.
For earlier versions of centos is a slight different. For CentOS 7 follow the steps.
Turn on the machine
At the boot menu, press
e to edit the existing kernel (Core) as shown below.
Scroll down
Change
ro to rw and start into bash shell by adding a simple line of command
init= /sysroot/bin/sh
Press
Ctrl + X to boot into Single User Mode
You will get a # prompt. Enter the following command
chroot /sysroot
Then run the command to change password
passwd root
If you want to change password for other users than root use the same command changing the username.
passwd ratheesh
if you dont know the user login name just go through /etc/passwd file. For that enter the following command.
cat /etc/passwd
First field is the username or login. Here on the above image rpb is the login and Ratheesh PB is the full name of that user. if there are a lot of users you can use more or less command to sees pagewise
more /etc/passwd
less /etc/passwd
or you can use the following command to list only usernames
awk -F':' '{print $1}' /etc/passwd
If you want to get list of all users other than built in system users use the following command
awk -F':' '{if($3 >= 1000 && $3 <= 60000) print $0}' /etc/passwd
after all changes update these changes and reset the boot parameters, use the following command
touch /.autorelabel
exit and
reboot the machine
Login using new password....
