====== Modify The System Bootloader ======
**General Information**
Managing Grub2; the system boot loader.
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===== Grub2 Structure =====
**Grub2 files:**
* /boot/grub2/grub.cfg => grub2 generated menu (**do not edit directly**)
* /etc/default/grub => grub2 variables (**can be edited**, then menus re-generated)
* /etc/grub.d/ => individual files used internally by grub2
**Grub2 symlinks**
* /etc/grub2.cfg => symlink to /boot/grub2/grub.cfg
* /etc/sysconfig/grub => symlink to /etc/default/grub
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===== Grub2 Commands =====
**View the active kernel that is default for system boot**
grub2-editenv list
saved_entry=CentOS Linux (3.10.0-327.3.1.el7.x86_64) 7 (Core)
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**View list of kernels displayed on grub menu**
grep ^menuentry /boot/grub2/grub.cfg
menuentry 'CentOS Linux (3.10.0-327.3.1.el7.x86_64) 7 (Core)' ...
menuentry 'CentOS Linux (3.10.0-327.el7.x86_64) 7 (Core)' ...
menuentry 'CentOS Linux (0-rescue-15bdd5425c924660bb6c9979dc071d56) 7 (Core)' ...
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**Set default kernel for grub system boot (permanent)**
grub2-set-default 'CentOS Linux (3.10.0-327.3.1.el7.x86_64) 7 (Core)'
* Note: Copy/paste including the single quotes from the "grep ^menuentry" output
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**Changing Grub2 settings**
- Edit grub2 variablesvim /etc/default/grub
- After making changes, re-generate the grub2 menugrub2-mkconfig -o /boot/grub2/grub.cfg
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