LFCS Operation of Running Systems Practice Question
A Linux server's boot process fails after a kernel upgrade. The GRUB2 menu appears, but selecting the newest kernel panics. You need to boot the previous kernel temporarily to recover the system. Which command should you use at the GRUB2 menu to edit the selected entry's boot parameters?
⚠ Common exam trap
A common mix-up: candidates confuse GRUB Legacy's 'a' key for appending parameters with GRUB2's 'e' key for editing the entire entry.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Press 'e' to edit the selected menu entry, then modify the 'linux' line and press Ctrl+X to boot.
To temporarily modify boot parameters in GRUB2, you edit the menu entry by pressing 'e', adjust the kernel command line, and boot with Ctrl+X. This allows booting an older kernel or adding options like 'systemd.unit=emergency.target' without permanent changes. The other methods are either for GRUB Legacy or incorrect for this purpose.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Press 'a' to append parameters to the kernel line, then press Enter to boot.
Why it's wrong here
In GRUB Legacy (version 0.97), pressing 'a' allowed appending kernel parameters. GRUB2 does not support this; instead, 'e' is used for editing. Since modern Linux distributions use GRUB2, pressing 'a' will not work as described. This option confuses GRUB Legacy with GRUB2 behavior.
- ✓
Press 'e' to edit the selected menu entry, then modify the 'linux' line and press Ctrl+X to boot.
Why this is correct
In GRUB2, pressing 'e' allows editing the selected menu entry. You can modify the kernel command line on the 'linux' line, for example to change the root device or add 'systemd.unit=rescue.target'. After editing, Ctrl+X boots the modified entry. This is the standard method to temporarily alter boot parameters without making permanent changes.
- ✗
Press 'c' to enter the GRUB command line, then run 'boot' with the previous kernel path.
Why it's wrong here
Pressing 'c' at the GRUB2 menu enters the GRUB command-line interface, where you can manually load modules and boot an OS. However, simply running 'boot' without first loading a kernel with 'linux' and an initrd with 'initrd' will fail. This method is more complex and not the direct way to edit boot parameters for a single boot.
- ✗
Press 'Tab' to list available kernels, then type the kernel version and press Enter.
Why it's wrong here
The Tab key in GRUB2 may provide command completion in the command-line mode, but at the menu, it does not list kernels or allow booting a specific kernel by typing its version. Kernel selection is done by navigating the menu entries, not by typing a version. This approach is not valid for GRUB2 menu interaction.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Linux Foundation exam blueprint
This LFCS practice question is part of Courseiva's free Linux Foundation certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the LFCS exam.