General Unix questions
Here are some quick fire questions that I’ve made use of during the interview process. These are intended to get an idea of their basic knowledge. It can be a bit puzzling that whilst a candidate may know all about the internals of a storage enclosure, they don’t know how to locate a file with a particular name without using grep.
Answers aren’t always given because if you’re conducting an interview on this subject, you should probably know most of the answers
- What scripting languages do you know? I’d hope for at least one of ksh, bash or csh (roughly in that order: I despise csh mind). Ideally perl will be known to them (see later)
- What are setuid/setgid in relation to file permissions?
- What are setuid/setgid in relation to directory permissions?
- What’s a run level? How do Linux and Solaris Run levels differ? Solaris: What’s /etc/pathtoinst?
- What does mknod do? What’s a named pipe?
- How would you shut down a Sun system very quickly? (uadmin) How does it work? (Doesn’t go through run levels)
- What is an inode?
- What is a directory?
- What does init do? What does inetd do?
- What performance monitoring tools do you use?
- What’s PGP/GPG; Public/Private Key; Setting up trust
- What’s ssh? Setting up trust between accounts.
- X Windowing environment. How’s it differ from others? Setting up X on Windows/Mac’s?
- What’s VNC?
- Any database experience?
General questions
Whilst I like to ask open questions that should give plenty of opportunity for the candidate to answer fully, it’s still important to give the candidate a chance to sell themselves. Try some open ended questions such as:
- What project are you most proud of?
- What have you achieved which demonstrated overcoming adversity in some form?
- Where have you learnt the most that improves your skills?
- Why are you leaving your current job?
- Why do you want this job?
- Why should we hire you?
- Have you heard anything that concerns you?
Some to avoid:
- Personally, I think there is very very little merit in asking about the minutiae of commands such as sed, grep, awk, sort and other associated Unix command utilities. This is especially so when it comes to command line switches to various commands. I take the view that, so long as somebody knows what the command does, and can give some context, there’s little to be gained by knowing if the candidate knows the “-w” flag in grep searches for whole words. The man pages are there for a purpose, and I’d expect them to use them for such insignificant parts of overall knowledge.
And of course, more personal questions:
- What do you get up to when you’re not working?
- I notice you’re from
- why did you leave? (I interviewed a lot of antipodes in London, and always like to hear their reasons for travelling, and so on). - I see you’re interested in
- is it fun? (There’s almost always something of interest to talk about that’s a long way away from technology. Try to find it!)
Don’t forget some obvious ones too, because agencies are often too enthusiastic to e-mail cv’s without checking them:
- Are you able to work here for the duration of the position?
- What visa are you on? (Some foreign nationals may have restrictive work visas)
- Can you provide me with references?
and last, but far from least:
- Do you have any questions for us?
… It’s a two way process, and you should always give them the opportunity to ask. Don’t assume previous or subsequent interviewers will, but if you’re one of six or seven interviews give them some slack if they’ve asked them all already 
Don’t forget to thank them for coming along too.
http://www.leyton.org/2005/05/20/interviewing-for-unix-system-administrators/
