10 Most Likely Asked Linux System Administrator Interview Questions And Answers

An entry-level Linux System Administrator with less than 1 year experience can expect to earn an average total compensation (includes tips, bonus, and overtime pay) of ₹243,259 based on 94 salaries. An early career Linux System Administrator with 1-4 years of experience earns an average total compensation of ₹373,622 based on 638 salaries. An experienced Linux System Administrator with 10-19 years of experience earns an average total compensation of ₹909,839 based on 67 salaries (As per Payscale.com).

The average Linux Administrator salary in the United States is $95,019 as of August 27, 2020, but the range typically falls between $75,661 and $107,171. Salary ranges can vary widely depending on many important factors, including education, certifications, additional skills, the number of years you have spent in your profession (As per Salary.com)

Typical Linux System Administrator job roles include:

• Linux Administrator:
• Tomcat/Apache Server
• Senior System
• Administrator
• Senior Engineer (System)
• Infrastructure
• Administrator
• Senior Linux
• Administrator
• System Admin

Prepare for your next job interview with these top 10 Linux System Administrator Interview Questions highly asked in job interviews. 

1: You see a process “./myApplication” with PID 44556, how can you know where the file was executed from?

2: How can you check how long is the system running since the last restart and the load average on it?

3: You want to save the mysql DB “mySQLDB” to a file “mySQLDB.sql”, how can you do it?

4: You want to run a binary file, you have permissions to it, but it gives you “Access Denied”, what do you need to do?

5: Explain the Zombie process.

6: What are the differences between Cron and Anacron?

7: How can you change your server time zone to a Europe/France time zone?

8: How can you check the mail queue of an exim mail server?

9: Using perl, write a command that will print all the IPs, Bcasts and Masks configured on the server line by line.

10: Explain how kernel modules are signed for secure system boot.

1: You see a process “./myApplication” with PID 44556, how can you know where the file was executed from?

You can identify the path where the PID was executed by running pwdx 44556 and you will get the command executing path as an output.

2: How can you check how long is the system running since the last restart and the load average on it?

The uptime command can show you the current time, how long the system has been running since the last restart, how many users are currently logged on to the system, and the system load averages in the resolution of the last 1, 5, and 15 minutes.

3:You want to save the mysql DB “mySQLDB” to a file “mySQLDB.sql”, how can you do it?

You can use the mysqldump command to dump a database – mysqldump -u username -p mySQLDB>mySQLDB.sql

4: You want to run a binary file, you have permissions to it, but it gives you “Access Denied”, what do you need to do?

In order to run an application in Linux you need to add executable permission to the file: in order to change a file mode, you need to use the chmod with the required parameters – chmod +x .

5: Explain the Zombie process.

The Zombie process, also called a defunct process, is one that is already executed and still waiting in the process table. These are the child processes that are waiting for the parent to execute the system wait call. Remember that the zombie processes will not be killed by the kill call. It remains in the process table till the parent explicitly executes that system wait call.

6: What are the differences between Cron and Anacron?

Cron is a job scheduled to be executed at a later time in a Linux server. One example could be scheduled backups of log files or databases. Anacron is Cron which is used on a workstation or client which is not expected to be always on or connected to a network. While Cron can be set on minute-basis, Anacron can be set on a day-basis at the minimum level. Any user can set the Cron, but Anacron can be set only by a super user. Since Cron is set on servers that are up all the time, it will be executed at the scheduled time. Anacron does not expect the machine to be set all the time and hence is executed whenever the system is up and available.

7: How can you change your server time zone to a Europe/France time zone?

You need to link the file /usr/share/zoneinfo/Europe/Paris to /etc/localtime.

8: How can you check the mail queue of an exim mail server?

The exim mail server allows a quick and clean command to view the mail queue – mailq.

9: Using perl, write a command that will print all the IPs, Bcasts and Masks configured on the server line by line.

You need to extract the IPs from the ifconfig first, then run on each line and

get the required information –

ifconfig -a | perl -n -l -e ‘/ addr:([^ ].+)/ and print $1’

10: Explain how kernel modules are signed for secure system boot.

For Secure system boot, the Kernel modules will have a private key and public key. The modules are signed with private key and authenticated with public key. The Linux distribution by default includes signed kernels, signed boot loaders, and signed kernel modules.

Also, the signed embedded keys allow the Linux distribution to boot, install, and authenticate with secure Unified Extensible Firmware Interface (UEFI) thereby allowing secure system boot.

Linux system administrator needs to be very analytical and be able to effectively troubleshoot and resolve a variety of problems. Read our books HR Interview Questions You’ll Most Likely Be Asked (Third Edition) and Leadership Interview Questions You’ll Most Likely Be Asked to get a comprehensive list of questions to help you crack the HR round of your interview.