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Mastering Linux Administration: Interview Essentials

Operating systems English

Mastering Linux Administration: Interview Essentials

Test your knowledge of essential Linux system administration commands and troubleshooting techniques. This quiz covers key concepts from permissions and process management to partition maintenance, ideal for preparing for technical interviews.

Sample Questions & Syllabus

Q1: Which command is used to change the owner of a file or directory?

chmod
chown
chgrp
chown-owner

Q2: What is the standard ID used for Logical Volume Management ($LVM$) partitions?

82
83
8e
fd

Q3: If a partition is reporting a 'read-only' error, which command can be used to remount it as read-write?

mount -o rw,remount /
remount -o rw /
fsck -y /
chmod +rw /

Q4: What is the primary difference between 'hard' and 'soft' mounts for $NFS$?

Hard mounts are faster than soft mounts.
Hard mounts retry until the device is found, while soft mounts give up.
Soft mounts are safer for data integrity.
There is no difference between hard and soft mounts.

Q5: Which command-line tool is used to display open files and the processes that opened them?

netstat
ps
lsof
fuser

Questions in this Quiz:

Which command is used to change the owner of a file or directory?
- chmod
- chown
- chgrp
- chown-owner
Correct Answer: chown

Explanation: The $chown$ command is used to change the file owner, whereas $chmod$ is used to change file permissions.
What is the standard ID used for Logical Volume Management ($LVM$) partitions?
- 82
- 83
- 8e
- fd
Correct Answer: 8e

Explanation: In Linux partition table types, $8e$ is the hex code designated for $LVM$ partitions.
If a partition is reporting a 'read-only' error, which command can be used to remount it as read-write?
- mount -o rw,remount /
- remount -o rw /
- fsck -y /
- chmod +rw /
Correct Answer: mount -o rw,remount /

Explanation: The command $mount -o rw,remount /$ is used to change a mounted partition's status from read-only to read-write.
What is the primary difference between 'hard' and 'soft' mounts for $NFS$?
- Hard mounts are faster than soft mounts.
- Hard mounts retry until the device is found, while soft mounts give up.
- Soft mounts are safer for data integrity.
- There is no difference between hard and soft mounts.
Correct Answer: Hard mounts retry until the device is found, while soft mounts give up.

Explanation: A hard mount keeps trying to reach the $NFS$ server indefinitely, which can block the system if it's unavailable, while a soft mount skips the operation after a timeout.
Which command-line tool is used to display open files and the processes that opened them?
- netstat
- ps
- lsof
- fuser
Correct Answer: lsof

Explanation: $lsof$ stands for 'list open files' and is the standard command to see which files are being accessed by which processes.
What does the presence of '$!!$' in the $/etc/shadow$ file (or password field) usually indicate for a user account?
- The user has no password.
- The user is logged in.
- The user account is locked.
- The user is a system administrator.
Correct Answer: The user account is locked.

Explanation: In the $/etc/shadow$ file, the '$!!$' (or sometimes a '$!$') indicates that the user's password has been disabled, effectively locking the account.
Which tool would you use to verify if a specific port or service is actively listening on a network interface?
- ping
- netstat -anultp
- ifconfig
- nmap -listen
Correct Answer: netstat -anultp

Explanation: The $netstat -anultp$ command (or its modern equivalent $ss$) is used to list active network connections, ports, and the associated services.
How can you identify a 'zombie' process in Linux using the $ps$ command?
- Look for processes with the status 'Z' or marked as '<defunct>'.
- Look for processes with a high PID.
- Look for processes using 100% CPU.
- Look for processes running as root.
Correct Answer: Look for processes with the status 'Z' or marked as '<defunct>'.

Explanation: Zombie processes are terminated processes that remain in the process table because their parent has not yet read their exit status; they are marked with 'Z' or 'defunct'.
What is the primary benefit of using $YUM$ over manually installing $RPM$ packages?
Correct Answer: $YUM$ automatically handles package dependencies.

Explanation: $YUM$ (Yellowdog Updater, Modified) is a package manager that automatically resolves and downloads dependencies from repositories, which $rpm$ does not do.
What is the correct command to view the size of a specific directory or file in a human-readable format?
- ls -h
- size -h
- du -sh
- df -h
Correct Answer: du -sh

Explanation: $du$ (disk usage) with the $-s$ (summary) and $-h$ (human-readable) flags is the standard way to check the size of a file or directory.