100 Essential Linux Interview Questions to Score 80% or Higher

This resource presents a collection of Linux interview questions designed to test fundamental knowledge required for system administration roles. The questions cover a range of topics including daemon scheduling, device classification, command functionality, file permission management, package ownership, runlevel changes, cron job configuration, and basic bash operations.

cron daemon purpose: D. Manage system daily task scheduling.

Block device example in most Linux distributions: B. Hard disk.

Command that displays one page at a time: C. more.

Command to check current directory space: A. Use df.

Command to change file permissions: B. chmod.

Find which package owns /etc/my.conf: C. rpm -qf /etc/my.conf.

Change runlevel from 3 to 5 without reboot: B. telinit 5.

Command to modify IDE hard‑disk settings: C. hdparm.

Command that lists one‑time scheduled tasks: D. at.

Effect of set PS1="[\u\w\t]$"; export PS1 : B. Change the command prompt.

Location to place a default .bashrc for new users: A. /etc/skel/.

Purpose of the export command in bash: C. Set environment variables for other applications.

Correct permissions for /etc/passwd and /etc/shadow on a shadow‑password system: C. -rw-r--r-- , -r--------.

Command to delete a user and their home directory: C. userdel -r.

Cron expression to run mybackup at 13:00 and 20:00 Monday‑Friday: B. 0 13,20 * * 1,2,3,4,5 mybackup.

Command to unmount a mounted filesystem: A. umount.

Default file permissions when umask is set to 022: D. rw-r--r--.

Command to locate the binary Xconfigurator : D. which Xconfigurator.

Command to mount all filesystems defined in /etc/fstab: B. mount -a.

Permission not required to execute a script: A. read.

These questions aim to help Linux operation engineers quickly review core concepts and improve their performance in written examinations.