Hiring a junior Linux System Administrator can be a challenging task, especially if you are interviewing for someone who is above your own Linux skill set! How do you know for sure that they are going to be any good at what they say they can do? What are the best interview questions to ask a junior Linux System Admin? In our experience, the best way to gauge an employees skill set is to put them in front of a command line interface and have them execute a number of straightforward tasks. Oftentimes, candidates will say that they have strong skills in Linux, but when confronted with an actual problem, they don't have the "tools" to fix it themselves. So, what we look for is a candidate's ability to use tools, rather than their ability to fix a particular problem. Employers are typically looking for candidates with the following skill set. Typical Job Description: for a hosting company Providing technical support for Level I-II issues via helpdesk and the telephone. Monitoring servers for stability and taking both proactive and reactive measures to correct and prevent issues. Providing fellow system administrators and support representatives with technical support and guidance. Assisting clients in transferring accounts to our servers. Installing, configuring, and maintaining services such as Apache, MySQL, and Postfix across multiple servers. Typical Employer Expectations for Skill Set Strong written and verbal communication skills Ability to work well with a team in a fast paced, constantly changed environment Ability to follow instructions from supervisors and senior colleagues. Outstanding customer service skills and a dedication to the customer service experience. Dependable to be at work during assigned shifts and to complete work as expected. Available to work emergency services 24/7 if required. Advanced knowledge of cPanel/WHM control panel. Advanced knowledge of the Linux operating system. Knowledge of bash and Perl shell scripting. Advanced knowledge of in Exim/Postfix/SendMail etc.. Advanced knowledge of Apache. General Understanding of PHP, MySQL and HTML. The Test We use some of the following questions as part of our interview process. These questions are designed to see if a person possess a baseline knowledge of Linux command line utilities. 1) What is the 1st line of a perl script? 2) What is the 1st line of a bash script? 3) What is the command that finds the location of an executable within your path on a server (ie. perl or grep) 4) How do you enable php4 for a directory within a site that requires php5 for all other directories - on a cPanel server? 5) How do you determine the hardware of a running system? 6) Update the locate database 7) Exclude /home/sites from the locate database 8) Find all of the processes started by “httpd” particular user and kill them in a one liner. 9) List all of the open files in use by root 10) Display a list of files that are in a particular directory which are owned by USER and have the permissions of “–rw --- ---“ 11) Where does cPanel log httpd errors? 12) Setup a key from from Server A to Server B. 13) Use chkconfig to stop a service from starting 14) On the test server, (as a bash one liner) a) Schedule the following task to run hourly b) List all users IP’s that experienced a fav icon not found error, c) Sort the data by IP Address, d) Count the number of time each IP was affected, e) Put that report into a file f) & email the report to hosting@LinuxForum.com. 15) rsync the following directory _____ to the following directory______. (excluding all .tar files) 16) using netstat, report back how many tcp connections are in `LISTEN` state 17) dig the mx records of LinuxForum.com 18) List the iptables rules w/ line numbers 19) Drop line 10 of an iptables rule 20) Blacklist an IP 21) Change DNS locally on the server to use Google's 8.8.8.8 server 22) Schedule the server to restart at 2am by command line 23) Determine if a service is running 24) Stop a service 25) Add a database for a new website 26) Create a one-liner that does the following task. A) Generate a report of all IP addresses that appear in access log file from today. B) Count the number of times an IP appears in the report. C) Determine what is the 5th most active IP address, D) Return the second set of 3 digits. ie. ***.168.***.***
