Step-4 (Check whether it is added to the default entry) Note you can change the 3 according to your choice of entries this is the default entries to boot. These command is use to set the entry as a default. Menuentry "Windows 10 (loader) (on /dev/sda1)" Step-3 (Change the default boot entry) Password: Step-2 (List all the GRUB2 boot entries) # grep "^menuentry" /boot/grub2/grub.cfg | cut -d "'" -f2ĬentOS Linux 8 (Core), with Linux 3.10.86_64ĬentOS Linux 8 (Core), with Linux 0-rescue-7e890c03ebb940a9a67163adaef14894 This guide provides to change the default GRUB Entries as well as to change the timeout according to the user requirements on respective Enterprise Linux that supports the GRUB. The GRUB has advanced feature as well as some basic features that makes it effective on all enterprise grade Linux. It provides a menu which shows all the the operating system in one place. It load all the Linux Distro as well as other operating system with ease. In case these steps help to resolve any technical issue then please do share your comments in the comments section below.GRUB is the default boot loader for AlmaLinux / Rocky Linux / Amazon Linux.
#Edit grub centos 7 password
By default root password is the single user mode password on CentOS 7 / RHEL 7 Servers. Note: In production environment, Single user mode is also password protected. Once you are done with the changes, type “reboot -f” command to reboot your server :/# echo “Enter-New-Root-password” | passwd -stdin root Let’s assume I want to disable network manager service and rest root password, run the following commands: :/# systemctl disable NetworkManager Step 3: Mount the root file system with chroot command :/# chroot /sysroot Once done with the changes press ‘Ctrl+x’ Replace “ ro” with “ rw init=/sysroot/bin/sh” Step 2: Press ‘e’ and go the line with starts with ‘linux16’ Step 1: Reboot the server and go to the grub menu and select the appropriate kernel Once you are done with troubleshooting Type ‘ exit‘ command two times or ‘ reboot -f‘ to reboot your server. Now you can edit the files and scan corrupted file system with fsck command. Run the beneath commands sh-4.2# echo “New-root-password” | passwd -stdin root Let’s assume we want to reset root password.
Step 3: Now remount the /sysroot in ‘rw’ mode switch_root:/# mount -o remount,rw /sysroot In the next window we will get single user mode or emergency mode, something like below: Type “ rd.break” at end of line which begins with linux16 and then press “ ctrl+x”
Step 2: Press ‘e’ and go to the end of line which starts with ‘linux16’ word. Step1: Reboot your Server and go to Grub boot loader menu and choose the appropriate kernel, example is shown below: There are two methods through which we can boot CentOS 7 / RHEL 7 servers in Single User Mode.
On the contrary we can also enable specific service from single user mode. So in that case we can disable that service from single user mode. Disabling / enabling Service – There can some service which is taking lot of time or delaying the boot.So to resolve and fix such issue, we need to boot Linux servers in Single User mode.
I got the request to reboot the server, so while booting up it got stuck while mounting that file system.
#Edit grub centos 7 update
Fix Wrong entry of fstab file – Let’s suppose I have created one file system on RHEL / CentOS Server and update the /etc/fstab file, but there was some typo while updating the file system entries.Repairing file system – There are some situations where OS(operating system) file systems got corrupted and while rebooting server didn’t come up, so in that case we have to repair file system by entering into single user mode.Reset Root password – There can be some scenarios where someone from the team has reset the root password and he/she didn’t share it with team and left the organization.Following are the scenarios where we need to boot our RHEL / CentOS Servers in Single user mode: Single user mode is considered as maintenance or emergency mode where we can perform our troubleshooting steps. For Linux system admins, booting RHEL 7 / CentOS 7 servers in single user mode is the most common day to day activities.