Modifying GRUB2 Boot Configuration (CentOS)

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Modifying GRUB2 Boot Configuration (CentOS)

The GRUB2 bootloader provides many improvements over its predecessor GRUB. This includes support for UUIDs, LVM, and RAID, and a more programmatic approach to configuration. In this hands-on lab, we have been tasked with updating the GRUB configuration and applying these changes.

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Lab Info

Level

Intermediate

Last updated

Sep 21, 2025

Duration

30m

Challenge

Update /etc/default/grub
Use a text editor to edit /etc/default/grub and ensure that the following options and values are present:
```
GRUB_TIMEOUT=45
GRUB_DEFAULT=saved
GRUB_SAVEDEFAULT=true
```
Challenge

Create a Custom Menu Entry

Copy the menuentry for a line that starts with menuentry 'CentOS Linux (3.10...) /boot/grub2/grub.cfg and add it to /etc/grub.d/40_custom.

Once copied, remove the rhgb and quiet options from the kernel line and change the title to Verbose Output Enabled.
Challenge

Create a Backup of the Configuration File
Use the cp command to create a backup of grub.cfg.
```
cp /boot/grub2/grub.cfg /boot/grub2/grub.cfg.bkp
```
Challenge

Generate a New Configuration File with the Changes
Use the grub2-mkconfig command to generate a new grub.cfg file.
```
grub2-mkconfig -o /boot/grub2/grub.cfg
```

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