Popular Linux Interview Questions for DevOps Interviews

[@tutoriaLinux]

1:11 - Basic Linux Interview Questions (ssh, ls, cd, cp, pwd, rsync, systemctl, df, du, ip addr, ip route) 4:55 - Slightly more advanced Linux (init, systemd, systemctl, journalctl, some linux philosophy, /proc filesystem) 8:01 - open-ended questions and troubleshooting (top/atop/htop/glances, lsof, /proc, ss or netstat, inodes) 11:05 - discussing past projects, planning a hypothetical implementation/project

[@jaypatel721]

I have had what are cgroups in an interview

[@CardenasSimon]

A few questions that I see are missing, and I use quiet often: 1. How would you automate the execution of a daily script (expect to hear cron). 2. You want to check the logs for an apache / nginx server, but you cant find them in /var/log/, where would you look (expect to hear how to identify where apache / nginx is installed, and check into their configs, where the logs are going) 3. How would you access a web service running in server B only accessible from server A, to which you have access, but from your local machine (expect to hear ssh tunnel using port forwarding -L or proxy socks -D). Great video though, I need to improve my skills on /proc and inodes, I only heard of those things, but have never dig into. Thanks!

[@nahuelgavilan6609]

Can you give a solution for your answers? It would be great for us to learn. Thank you very much!

[@FloresFactor]

@@nahuelgavilan6609 x2

[@manuelugarte9859]

@@nahuelgavilan6609 I think as a process of learning we should google these as a youtube comment can be sometimes too small to have a full answer, plus even searching in google you will find a vid of it ;)

[@bitti1975]

I think for 2. using lsof is a more direct and reliable way to figure out where a process writes its logs, at least if you have enough permissions that is.

[@laurakamil8640]

also what is the zombie process

[@ibrahimosama5236]

Been working with linux for 2 years and I only knew about proc today, awesome video thanks mate

[@RandomShowerThoughts]

Questions I've been asked in the past month interviewing Difference between a process and a thread? What command used to find processes as well as cpu and memory usage? What is the difference between a L4 and L7 load balancer? Find the disk space on a machine? Find the open ports on a linux machine?

[@jimbarino2]

Have to say, I've never heard it pronounced "system-cuddle". Sounds like what you do to keep warm in those chilly data centers...

[@markinthecloud]

James Baird I’m fairly sure he’s saying “cuttle” as in “ctl”

[@deanmc]

First time hearing it myself. I like it because it requires less syllables. Like saying World Wide Web instead of WWW 😁

[@robi1kenobi]

@@deanmc Or even shorter - dub dub dub :)

[@tubejim101]

lol. I thought it was just me :)

[@stephenmount6181]

Yeah, it is ctl but system cuddles are actually what "Remote Hands" is for with co-location providers, they remotely give your broken server a hug and/or reboot. Fixed.

[@anthonymignona4146]

Thank you for creating a concise yet thorough video, not only for this Linux interview video, but also your other one as well.

[@ukaszboczkaja4829]

Not strictly for devops but.... the best question i came up with to test candidates knowledge and their experience would be the open one that assumes certain scenario in infrastructure: Say we got an application that its architecture solely comprises of httpd and mysql (as an example) running on single server at the moment. Lately the application has gained popularity and its userbase has risen exponentialy to the point where we experience problems with performance. Given unlimited budget (we are free to buy as much hardware as we wish, scale horizonally or vertically) how would you go about increasing performance and availability of the application? Now just let them talk, see how wild they can go with improving architecture what technologies they would use etc. Apart from infrastructure improvement they would get extra points pointing out the need to cooperate with programmers on revising their application code and sql queries to check for any inefficiencies.

[@yash_renaissance_athlete]

If we are talking about using a cloud provider like AWS, then For the application servers (httpd) , I'd say introducing elasticity and Fault tolerance to the architecture using say, Auto Scaling Groups and attaching it to a Elastic Load Balancer configured with relevant health checks. If the application is used globally, then we can use CDN like Amazon CloudFront. Then, for the database servers, we can have read replicas which would balance the READ queries amongst them and WRITE queries would be handled by primary node. Also, how can I forget caching. Redis is love but ElastiCache can be the rescuer here ;). At the programmatic level for DB, we can implement sharding.

[@emmanuel.n8458]

Scale up your instances, use load balancer, r53 ,auto scaling to handling traffic n availability. I have 0 experience just what I learned on my free time

[@nileshjoshi100]

How traceroute works? What are signals in Linux? How kill command works in Linux? How passwd command works with permissions 400 on passwd file? How you identify if particular device have filesystem on it or not? These are some interesting questions I love answering or asking to gauge Linux knowledge..

[@ki4dbk]

Again, I wanted to say thanks. I worked as a Linux sysadmin in the mid 90's to 2000, and I'm knocking off the rust now.. ..learning git, etc. Tnx again.

[@NerdyEd]

Another great "documentation" command is apropos - great for finding commands you forgot or commands you may need. Try it sometime.

[@__astroverse]

also $man -k :)

[@DIYDad1]

Good video, I’ve gone through a ton of interviews over the past 6 months, some companies ask really simple screener questions like what is dns, and some get far more technical. Depends on the job and what sort of specialties they want with someone. Most jobs I’ve seen these days there is very few postings for infrastructure or sysadmin jobs anymore. They are few and far between. My entire infrastructure and engineering department of 250 people were recently outsourced. Probably 90% of the jobs around here are for cloud, database, software, and devops those are hot button buzzwords in the industry right now. The best interviews aren’t the most technical questions but asking what I do in my free time, what am I interested in, do I have a home lab that I tinker with, what tech blogs do you read, and so forth. The good companies want someone they can live with day in and day out and get along with others in their team. They smart companies hire someone with a personality. As long as you have a passion for learning and bettering yourself a lot of the deep technical skills can be trained on the job. At least that’s what I’ve seen as of late after applying for over 90 jobs in IT since March.

[@cryptobarn9445]

@DIY DAD what jobs were you applying for and which one did you finally get, a sysadmin job or something related to the cloud? How long did it take you to land the job after applying for over 90 jobs?

[@kellyclarke8754]

The people I have interviewed with were all about the tech knowledge and how fast can you spit out the answer.

[@kIrani1]

I completely agree with you. You can teach the technology to someone who has basic knowledge and capability, but you can not teach personality and behavior to people. Unfortunately, most of the companies that I was interviewed with were not professional and were asking multiple technical questions that you might've forgotten at that moment! Also, they are looking at you as well, and the older you are, the less chance to hire! That's the true and sad story of these days hiring managers or HRs even at the big companies after tons of interview experience!

[@nahum35]

Probably one of the best Linux interview questions!!! thank you very much!

[@EngineeringVignettes]

/proc is fun and all but when you get into /sys (the sysfs) then things start to get interesting... cause that's where all the knobs and switches are. The virtual directory /proc was never really intended as an interactive system, only to be read for process information. sysfs (sys/) is where the drivers can expose their tuning parameters and where platform _classes_ and _buses_ are enumerated. Thanks for the example questions. Cheers,

[@shanebagel]

Wonderful video! Even if you're not interviewing this is super helpful

[@nauticaorangewatchbg9923]

I had a interview yesterday, and i watched this video prior to my scheduled time, and they asked me one of the question that was here, so i started laughing, and they asked what is the problem, and i said that i watched this video day before lol :D Atmosphere was quite good, so it wasn't weird :D

[@Zancb]

Did you get the job? :)

[@germieb]

wow you make me feel better, been a sys admin for 18 years at the same job and thought a new job might have tough interviews these days but nope this sounds super easy.

[@charleskusi7791]

Excellent content 👌🏾 Thanks!

[@desheen5056]

you are the best, thank you

[@PetrOsetr]

King! Interesting questions to listen to indeed :)

[@Ather178]

Thank you so much for sharing this!

[@syednadeembe]

See you in the next one. This one is 10/10

[@gleventhal]

You dont have to grep for ESTAB using ss, you can filter on state = established

[@MarcinWojtczuk]

Thank you very much for helping out the community. I feel also more a dev than sysadmin, but your knowledge of troubleshooting is really extensive. I become worried that I've never heard about journalctl, but that's because in my youth I've only inspected /var/log/*. I never had to resort to doing any tcpdump in practical work, and so also netcat is not that useful, compared to debugging power of curl. I hope that if you see someone sees ways around linux in general, he/she would pass. At some point during lazy studing days, I've built Gentoo from scratch. I knew ways around that beauty, but I'm really lost in RHEL now. Like the damn LVM and allocating volumes for docker images....

[@alcap6145]

Hey man your videos are great I'm using them to prepare!

[@whiskyone405]

Great Vid, thanks for the information and keep up the good work. Are you able to give an example of a simple DevOps project. What is a normal day to day task working in DevOps? Thanks.

[@lmaced0]

EXCELENT, thank you!

[@johnjohns6872]

Thanks for this great video !!!

[@md.imamulislam7]

systemctl commands are okay, until you start using something that doesn't use systemd. One should know that service commands change with init systems. I learnt it the hard way when trying to use Void Linux.

[@Shvmadogg]

I would use archwiki as well as man pages

[@1nt3rnetz]

kzbin.info/www/bejne/fZXVm4eMecqff5I

[@tutoriaLinux]

Haha yep, it's a little easter egg in the video :-D -- I love the arch linux wiki and use it as one-stop shopping whenever experimenting with some new userland software. It's also GREAT for things like systemd.

[@zapador]

I always tell "Windows power users" that want to switch to Linux and not feel like "just a user" to install arch. The wiki is excellent and it'll teach you a lot about what Linux is as opposed to just installing Ubuntu or whatever.

[@zameerahmed1775]

Good q's ....... ideal DevOps Manager.

[@Facebookmovies12345]

Question: What is the difference between an orange, and a blood orange? I answered blood oranges have a slightly bitter taste, and are superior to regular oranges. I was hired right on the spot. Thank you tutoriaLinux!

[@somethingnew3338]

More interview tutorials. Thanks a lot ☺️☺️

[@pomeyaziz7062]

Very helpful video..... 😍😍

[@dj.coda.newyork]

After seeing this, I decide to give up the DevOps track.

[@tisd]

Create a tutorial on Linux troubleshooting.

[@Stayfly81]

Thanks tutorialLinux. The first couple I was able to answer with no issues

[@Fractal227]

The video by itself is pretty good, just casually talking about a distribution and some specific Linux stuff. But if you called me up to talk about a interview and asked me these questions, i would think "is this guy serious?". What job level are we talking about here, support? 1'st / 2'nd level? something else? A Linux interview question i have been given that i thought was strange (something like) 1. How do you aggregate and count identical lines in a file represented by a integer. cat file.txt|sort|uniq -c 2. By reading this output from Apache webserver, what is a probable cause that the service wont start? Given 3 A4 paper's with output. 3. What is the biggest mistake you've ever made on a server? If anyone out there get such a question, have the balls to ask "what is the biggest mistake you've ever made?" and wait for them to move on.

[@RootsterAnon]

I just found out about egrep and that it is older command that can be replaced by grep -E "(ESTAB|LISTEN)". I didn't know it even can do that so tnx!!!

[@EasonTek]

system-cuddle i say SystemCTL, nowdays i use service or rc-service because systemd has some drawbacks

[@daniellaerachannel]

a video about "Most common linux commands for software developers" would be appreciated ! thanks a lot

[@Zancb]

There's probably 100s of videos already on that.

[@pgoeds7420]

5:05 There you are - systemd is an elephant.

[@pogo55555]

Liked. Subscribed.

[@borowich694]

Thanks for the video !! Still have a lot to learn but i think am in a good way !! ;)

[@MrSandshadow]

Linux is such a vast system that even after 5y of being developer I still have 'no idea' what I'm doing. Are there any courses/materials/books that you would recommend to up my linux game a noch?

[@ashearera]

I found comptia linux+ filled a lot of the gaps for me.

[@boitenoire-k7x]

How Linux Works

[@ibelieveinliberty5226]

How would you poke around /proc to see what the command was called with?

[@SuperGianluka88]

More than DevOps this are sysadmin questions

[@muddasirkhan805]

DEVOPS is a METHOD

[@foxlance]

If you havent ran out of inodes, you havent been rolling out and maintaining servers enough, :D

[@Uc9uE3pKsS6uQ]

what is the most valued Linux Sys Admin certificate ? thanks!

[@tadeubernacchi3360]

Great video, I'm always watching your channel, one of the best for tech's. What do you think about Application Engineers? Thank you

[@SuperRahtube]

also we need to know how to patch a Linux system like Redhat, SuSE, Ubuntu etc. and we need to know how to create a patch repository

[@aaronchamberlain4698]

Now my question is how I find such interviews. Based off what I do day to day I would say I would nail your interview. I’m looking to move to a more Linuxy job but they all say “you need 3 years of Docker and Security+ and and”

[@juanmanuel7305]

Nice helment dude, it suits you

[@devpokhariya7093]

Thanks ! Man For this video. I was searching questions I can get in interview. You uploaded this on right time for me. And also I would love if you can give some more references I can look to crack linix interview. some website or videos. Thanks

[@tutoriaLinux]

Good luck! I've got a whole list of my favorite resources here: tutorialinux.com/sysadmin-learning-resources/sysadmin-software-books/

[@frannelk]

I got these 2 questions on my last Linux interview: 1) How to delete a file which is zero bytes and its name is -xf? This really pissed me off because you never has files with special characters and with zero bytes.....I mean you can go an challenge someone with systems but this question...Pleaae...and this one you can figure out quickly if they give you a console to try, but with with pen and paper no straight forward. 2) What is chroot for and provide an example? This one is very good and they caught off guard, well good lesson to learn.

[@blackbroadcast1274]

rm ./-xf? What is the significance of 0 bytes?

[@chuksc-m.5579]

@@blackbroadcast1274 rm -- -xf or rm ./xf . I do not know why the zero bytes would be significant though.

[@dwightnearing1652]

for the file you could delete it by its inode id as well.

[@КириллБикшанов]

How inodes works. Great question.

[@nnutipa]

Unlinked(deleted) files is also a good topic. How does linux memory work? And of course some shell basics.

[@jamessmith1652]

Great video but more for a sysadmin role. I love Linux but honestly half of this is no longer required in DevOps and unreasonable to expect of a candidate. They might have used all of these things at least once but will have forgotten much of it because so much is now abstracted away e.g. more concerned about Kubernetes objects.

[@tutoriaLinux]

That's true, the industry is currently super k8s-heavy, so I agree with you on a practical level. On the other hand, how do you troubleshoot k8s issues if you don't understand the basics of Linux? I guess if you use a managed k8s service and just write yaml files, but then you're probably more on the "dev" side than the "devops/SRE" side. That "devops" title (which, I know, was never supposed to be a title) has definitely shifted meaning over the last few years. No idea where we'll end up in a few years with all of this.

[@oldies81]

Hi What is the best Linux course and what study material do you recommend.?

[@Fractal227]

There is no material as such i would recommend, a Linux distro is alot hands on. Want to setup a webserver? Go to digitalocean.com E-mail server? techmint.com and trial and error. Get to know the shell? 'apropos keyword' Get in touch with a forum like ubuntuforums.org Some will say Linux+ as study material, but dont overcomplicate things. My advice for learning a Linux distro 1. Get an idea for a project 2. Use google, Linux forums and one of the above sites if your project fits in. 3. Ask questions 4. Dont be afraid to try stuff, a virtual machine is great for this. The biggest hurdle is knowing how to keep moving if you get stuck on something, either a system command such as apropos, man or something else. forums, a individual, Google and so on.

[@carlosfernandez6470]

Sir , can you help me with a problem that i can not find the way out. I had an old hp laptop that i installed kali linux , but in the process of installation it doesn't recognize my network(wifi) and i skip the step. Now i have the linux running perfect in the laptop but i can't figure out how to connect the laptop on internet. Thanks in advance , i know is a noobie question but i am stuck. Thanks for your help

[@sin5946]

carlos fernandez be hardcore. Write the driver for yourself.

[@carlosfernandez6470]

Dávid Hlavati don't know how

[@peetk5993]

kali linux is not for people who cannot figure out such a problem. install ubuntu.

[@GaryMcNeely]

thank you

[@bitelogger]

To be honest the only question I lost was the last one about the binary. It is possible could you explain a liltle more about it? Thanks in advance.

[@fpgist]

The one I was asked which I didn't expect was: If someone changed the permissions on the CHMOD file. How do you change it or fix it.

[@Uc9uE3pKsS6uQ]

the owner on the file can change these permissions chmod is command to set these permissions

[@FilipMakaroni_xD]

I've ditched Windows years ago and I'm using Linux 24/7, to me it was the most interesting when I didn't know something that is even basic lol Also I kinda got scared of inodes and the implementation part

[@josephfilla3573]

Inodes *are* the file. Not just a data structures

[@ciprian-nedelcu]

I am so far behind :)

[@tutoriaLinux]

Don't get down on yourself. All of this stuff is learnable in a reasonable amount of time. Often, just *knowing* which subjects you're weak on is the most important step. Once you find an area that you need to improve, you can easily get the basics down with a few weeks of reading and experimenting. Don't get discouraged!

[@mstoon3891]

How far have you come since you posted this comment?

[@SaurabhBadhwar]

How about checking the knowledge on the limit of processes one user can run, how to check it and how to change the max limit of the user's process for hardening the server's security. BTW this video is awesome (Y)

[@joyo2122]

interesting video

[@mariangasparovic6200]

Great video, but I cannot resist - you mention not to allow root login and then in rsync example you use root@xyz

[@tutoriaLinux]

Hah, yeah, I felt extremely guilty when I realized that the default Ubuntu 18.04 box on DigitalOcean (which I used for the quick shell examples in this video) comes with root only. Double checked my key...double checked my ssh config...prayed to the tech gods...and yes, of course it was root@ in the end.

[@djone1897]

What storage q&a vmware

[@richardmaduka4747]

SYSTEM CUDDLE?? System needs a hug

[@MyTube4Utoo]

Shoot, I was hoping one of the questions would be; *"If you were a tree, what kind of tree would you be?"* I was ready for that one! (A Mighty Oak - btw) :-D

[@binbashbuddy]

Oh you're in trouble now....you've offended weeping willows across the nation!

[@MyTube4Utoo]

@@binbashbuddy *lol*

[@GradyBroyles]

Are the questions really *that* basic? I've assumed I needed a LOT mre easily demonstrable complex sys admin techniques. I'll be really honest, I'm sitting here a little like :-O -- why am I not working yet?

[@ixianghola1249]

Hey thanks for the video! I've been preparing for interviews and I found this to be a super helpful tool. I'm a recent college graduate who has some experience working in operations via internships, I guess you would call me a Linux Admin/ Operations Engineer? The roles were never to well defined. Since working in the industry I've loved Linux but never had to the chance to formally learn it (only really learned it in the field just working with it). Do you have any advice on learning linux aside from just playing with it? I often find myself getting stuck on the nitty gritty questions like how does proc work, How does linux even know to boot up, Grub, disk mounting, PIDs, UIDs, GIDs, jailing. Ideally I'd love to read a book or do a course that teach such concepts, any advice is appreciated!

[@lindas.4376]

I know this comes late, but he does recommend Unix and Linux System Administration Book. He has a few others on his website.

[@sandramoses9695]

I’m taking linux class. And it’s only for 6mnths. I’ll hook you up if you’re interested.

[@MyTube4Utoo]

Just a hunch, but I have a feeling Dave has worn out a keyboard or two in his computing career. *lol*

[@asdasdaasdasda4978]

if you have to use ssh, its not devops

[@SOCM]

I was thinking the same thing. Its my understanding that "Devops" is predominantly about getting rid of pets and becoming cattle ranchers.

[@quantummath]

dude your voice is a bit like that of Ownage Pranks :-D

[@irfan4701]

Logo around your face made you look like thanos...

[@Uc9uE3pKsS6uQ]

im in this for 15 years and never touch inodes I was forget what it is do not touch there

[@alikthenam]

Why talk about ssh if you plan to talk about /proc, init etc Don't waist energy, time and money. Start with deep things if he knows them he knows easier stuff

[@solidwaterslayer]

the only thing i understood is mv ls cd dir

[@joshuz101]

SYSTEMCUDDLE LMAO

[@nirvfan81]

Ugh. This videos all over the place. Also, don’t say cuddle in an interview.

[@tutoriaLinux]

It's a collection of common questions that get asked in interviews, so I think it makes sense for the video to jump around. Also, calling systemctl "system cuddle" is hilarious. Relax!

[@nodrubamogaw8853]

Total time waster wasted MY17 minutes...too many AAAAHHH, ridiculous..NOT helpful at all

[@apilgrim8715]

Thank you