Unix / Linux Interview Questions

[Ragni Singh]

Hello, all, I need to know what are the types of questions that are asked in a interview. If you have interviewed or in the process of being interviewed, please share with me sorts of questions that are asked. If you have a checklist with questions to ask, can you please forward that to me as well. I'm just trying to figure out what questions get asked in a unix/linux system admin position.

Points will be assigned.

[Rick Garland]

kickstart use, ftp client and use, Secure Shell configuration, security (the PAM modules), kernel configuration, xinetd, printing, etc.

These are just some of the questions I have been asked

[Ragni Singh]

Any Unix managers here that have done hiring? What kind of questions do you ask?

[Ivan Ferreira]

We use to take a short written test.

Questions really depends of the skill that you want that the candidate should have. Of course, you must ask questions that you really know the answers, so the answers cannot be considered as "may be right".

You should ask how many years of proven experience it has.

Is he trained to maintain a server? Manage user accounts, performance, security and patch the system.

Also, depends of the server type that will be managed, like Internet server, database server, file sharing server, etc. Is he trained to maintain that kind of server?

People that holds some certification, like RHCE, LPI, Linux+, Sair, etc. should have neccessary skills.

[Vincent Fleming]

Some basic questions are always good to weed out candidates...

I've started out with the "what is ____, and what is it used for?" with:
tar
cpio
whois
finger
bind
mount
fsck
ping
ifconfig
inetd
smbd

...and pretty much anything else you're looking for.

You can get specific with command-line arguments or file formats if you have specific requirements for the position - for example, "What is the meaning of the 3rd field in the /etc/passwd file?" (answer: user id)

Good luck,

Vince

[Ragni Singh]

Thanks, tell me more.

[Vincent Fleming]

You want more, huh...

Well, about 2 years ago I took a test from a NAS company... so they were very much looking for NAS-type usage. So, they had a lot of NFS and networking questions, such as:

what is DNS and what is it used for?
what does "mount -o ro ... " do?
what is the nsswitch.conf file, and what's it used for?
what is the difference between an NFS hard mount and soft mount?
what's samba?
in vi, what does ":g/fred/s//foo/g" do differently than ":g/fred/s//foo/" ?
Name a synonym for ":cw" in vi.
How do you set "vi mode" in ksh?


That's all I can think of offhand...

[Ragni Singh]

this is just great. Just keep em coming. POints will be assigned.

But I guess it really alldepends on wh is asking and what you are going for/

[Vincent Fleming]

Exactly...

When I've developed tests, I always try to include commands that are used often (daily), in great detail - the really esoteric stuff is only known by people that use those commands daily.

So, developing and grading tests, the more of the really detailed, esoteric stuff the applicant can answer, the better - but you can't expect them to answer everything correctly. Typically, they'll answer all or most of the questions on a particular subject either correctly or incorrectly - people tend to specialize - for example, they may score highly on networking, but not on backup software.

If you keep it too high level, someone who really doesn't know their stuff, but studied up for the test can score highly.

For example, with bind, you should be asking detailed configuration and debuging questions - what's a PTR record? what is the format of a PTR record? What's nslookup? What's the format of a /etc/mail/access entry?

Good luck,

Vince

[Paul Cross_1]

I like vincent's approach.
The questions you ask will vary deeply depending on the OS you are running of course.
Because this is a Linux forum, I am assuming you would need to ask linux specific questions like:
- lsmod, insmod, modprobe (kernel modules)
- kernel building, patching
- file system questions (difference between ext2 and ext3, what is a journalling file system?)
- how do you partition a disk? (fdisk)
- How do you export an NFS volume?
- You will definitely want to ask about the various packaging utils out there (RPM, Debian, aptget, etc.)

If you post the OSes that you use, we could come up with some more specific questions.

[Ragni Singh]

HI, this is just great. Currently we have Redhat linux running 3 and we have several HP-Ux servers running 11.0.

I'm not looking for a person to do just one job i.e, only security or patching. I need more of a general person who knows just about everything. we only have around 35 servers and expect that person to be able to do it all, if you know what I mean.

Keep the questions coming. Once I have enough I will create a cheatsheet and share it with all and can use it either to a interview or prepare to be interviewed.

[Ralph Grothe]

Hi Sanjit,

I think you yourself should know best what an applicant should know.

You know what kind of applications your servers are hosting.
From your own daily work you also know very well what are the typical mundane tasks of your sort of system admninistration in your place.

Then most of the times one would I think hire new staff because either the workload for the incumbent admins has become too high, and they pretty well know what sort of work they want to get relieved from and "burden" upon the new colleague(s).
So there you know what you require them to know about and be skilled in so that they can very soon be able to work efficiently unattended.
The other common situation could be that your site is emerging to new grounds and thus need s to extend their expertise by "fresh blood" preferebly already skilled in this particular area.
Then the requirements your new projets dictate will tell you what to look for.

But I wouldn't focus too stubbornly on the detailed skills and intimate knowledge of a particular OS or application of yours that the candidates should posses in advance.
I think any admin with several years of Unix experience should be flexible enough to catch up quickly with the special technical demands.
He should of course be willing to RTFM and ask his new colleagues questions whenever clarification is needed, without impeding their work too much, to close any gaps he might have.

So I consider it even more important that he is communicative with some degree of social aptitude.
Most important he/she has to fit into your team!
This means you also should take into account the (probably different) working styles and attitudes of your present colleagues and estimate (if this is at all possible in the confines of an interview) if the candidate's appearance would harmonize with them.

In general I would think that the so called "soft skills" are much more important than the technical skills (which I think can be more easily adopted by someone with a right foundation).

[Alexander Chuzhoy]

I was interviewed 3 weeks ago in some major company.
The technical interview included the following subjects:
* being able to work with files responsible for network.
* describe the steps to compile linux kernel.
* how do you setup nis domain.
* how do you setup dhcp server in order for it's clients to be able to load boot image.
* netapp appliance familiarity.
* Kickstart familiarity.
* Jumpstart server in Solaris familiarity.
* bash and/or perl scripts.
* DNS setup and maintenance.

[Vitaly Karasik_1]

- RPM
- what is PAM
- adding new harddisk; moving fs to the new disk
- cloning linux box, methods for backup/restore
- tuning kernel parameters
- tuning system limits

[Raj D. · Accepted solution]

Hi Sanjit ,

Here is few question that can help evaluating the skills :

1) Describe the boot sequence of a Linux system , or hp-ux system.?

2) How a system gets the default runlevel.?

3) What is the difference between init s , and init S. ?

4) How do you calculate the free space available , to increase/extend a filesystem.?

5) What is the procedure to mirror the root disk?

6) How to set kernel parameter from command line.?

7) What to do , if the newly build kernel doesnot boot.?

8) How to make sure if the patch going to install will take a system reboot.?

9) How to extend a filesystem online ?

10) Can you reduce filesystem size? If yes , how? Any risk ?

11) How to measure performance of a system , if the connected users are saying server performance is very slow ?

12) How many entry can be added in resolv.conf?

13) what is the command to see the default gateway?

14) How to sort as per the uid , from /etc/passwd file.?

15) A server is rebooted and came up, but you dont know if its planned or unplanned , how to check about it ?

16) How to find 10 largest file in the filesystem /user/sap/trans ?

17) How to check the error logs in the system.?

18) How to add a printer in the system?

19) How to write a function within a shell script?

20) How to disable the ftp service in the system?

21) How to multiply two numeric value , from the command prompt and to get the result. ( ex: 12 * 15 Result to be display = 180 ). ?

Hope this will help...

Cheers,
Raj.

[Ralph Grothe]

@ Raj,

just out of curiosity,
I was reading your exam just to see if I would pass the test.
I really stumbled over 3) the difference between s S runlevels.
Ehr, I always thought there wasn't any difference, and this is what the manpage of init insinuates.
Have I been missing something, and there is a subtle but vital difference?

[Piergiacomo Perini]

Hi Sanjit,
in my last interview technical boss
asked me " How do you proceed if
you have to set-up a Superdome ?".


regards

[Alan_152]

Grab yourself a copy of Nemeth's Unix System Administration Handbook. Chapter 32.9 has all sorts of good hints on how to execute an interview that I have used in the past

[Ragni Singh]

You guys have been great. Thanks for teh responses. Everyone deserves points.

[Florian Heigl (new acc)]

There is a lengthy mp3 about sysadmin job questions, both for employers and applicants at cuddletech.

see 'Audio Commentary 4.0: Tips on interviewing for UNIX positions:' at http://www.cuddletech.com/audio/index.shtml


Good luck in case You're the one being asked ;)

[Steven E. Protter]

I was asked once to do a find command on a real system for files three days or older.

Thats something someone with linux/unix experience could do.

find /tmp -mtime 3 ...

SEP

[sreekanthtm]

Interview questions at CSC ( Computer Sciences Corporation)
Profile - HPUX system admin

Hardware details of hpux servers, eg: Processor, RAM, Architecture ect
If an user complained that his server is running very slow, and you are the remote admin, how do you troubleshoot. Step by step

Command to reduce filesystem on LVM, (filesystem used is online JFS not Vxfs)
RAID Levels supported by LVM
Commands to config RAID 1 in LVM
How do you use tar cmmd for n/w backup
Protocols used by NFS

Iam also not sure about answers
How do you install Hpux remotely, using Ignite Ux

[Steven E. Protter]

sreekanthtm,

I believe this has been mentioned. Nov 8 2005 was last reply before yours.

This thread is dead and forgotten. I know you are eager to answer questions and get points. Someday I'm sure you will have more than me.

Please however stop cluttering the forum by openning up threads the owner clearly does not care about.

SEP