Hi everyone, I hope you can help me to understand my situation with Linux.

A couple of days ago I was contacted through Linkedin and received a job offer, the required skills were (In red what I have):

• +2 years of experience as a DevOps Engineer/Sysadmin with Linux systems. // I have 7 years in the Linux field
• Experience supporting Nagios, Prometheus, Grafana, Gaphite or ELK. // 5 years of experience with Nagios
• Implement Nagios plugins and maintenance in Perl, Python and Shell script // Yes, full Nagios friend.
• Automation/configuration management using Ansible // 2 years of it.
• Scripting/programming languages: Python, Perl and Shell // Python and Shell, Perl not so much.
• Strong Linux working knowledge (preferably RedHat/CentOS family) // Yeah, and many other distros.

And as a plus:

• Experience with Kubernetes: basic knowledge to add/configure new deployments, daemonsets, configmaps, etc.
• Experience with KVM and xCAT: basic knowledge of xCAT cli commands
• Experience managing monitoring tools at scale
• Experience doing basic AWS administration // Only in EC2
• Version control with Git or SVN // Yes, Both of them
• Familiar with Elasticsearch or Kibana

I went really honest with the RRHH girl, she presented my CV to the company and they liked it, so they sent me some "tests" to see how much I know about those requirements.

The tests were divided into 3 sections:

• AWS
• Programming
• Linux

In AWS they asked a lot of things, this was more than I knew.
In Programming, just to mention some of the questions they asked about:

• Bubblesort
• Polymorphism
• Encapsulation
• Abstraction
• Inheritance (this is ok)
• Linear search Algorithm O(log-n)
• Exponential Growing
• Constant time algorithms
• Logarithmic Algorithms
• Linear Algorithms
• Big O Notation
• Insertion Sort
• Merge Sort
• Binary Sort

And finally, in Linux, some of the questions were:

• How is recognized a second partition in GRUB (sda1,1), (sda0,1), (sda1,2)...
• What does cp -b
• What does /etc/services
• Default run level for X

I swear to god I've never used cp -b, and If I had to I just would use man to check it.

Same with /etc/services, In seven years working with Linux I've never used that file.

Grub is ok and run level too.

I feel like a monkey, should I must remember or know all of this? I mean, your ability to know Linux depends on if you have used a flag of certain basic command or certain specific file?

In programming, I was expecting some coding test but they went full theoretical.

I feel I know nothing and I don't know if all of that is common knowledge out there, what do you think?

I'd love to receive recommendations on Linux or programming courses to start learning some of this.

tosslove.

I have a vague knowledge of some of those terms, but I would have to look each up to be sure my responses were correct. You should just do that. Be careful to not just copy/paste from some article, but use what you find to "remember" what the terms probably mean to the interviewer and write your response from that.

IMO, no, those things aren't "common knowledge," and in some (maybe most) cases, knowledge of them isn't required to be an effective administrator or software developer. One's ability to know Linux (or any OS) mainly depends on one's ability to look things up.

Well the thing is you couldn't use any source to investigate, only what you knew and with 1 minute per answer. Anyway, I felt tricked by the job offer and the type of questions.

The thing is, you can really tell someone knows linux by the ussage of one command and certain specific o.s files? I'm quite agree about what you've said:

One's ability to know Linux (or any OS) mainly depends on one's ability to look things up

Sorry, I had to stop there.

Linear search algorithms are O(n).

Binary search algorithms are O(log-n).

Apart from that, just get a book on algorithms and a book that covers object-oriented programming (most introductory books on Java or C++) and read the first few chapters of each. Yes it's common knowledge and it's covered at the very beginning of every college or university programming curriculum. The actual point of the questions was to check if you'd gone to school for this.

Yup. RTFM wasn't/isn't only a distracting troll response. It's also commonly useful and meaningful in ANY field. No one person does or even CAN know it all, but the learned and skilled know how to find the "M"s.

Oh. I didn't realize the "tests" were as in an interview. Yeah, then all you can do is say "I don't know, but I know how to find out."

I have been programming web-based applications in perl for about 20 years for my customers and myself. My "day jobs" were all using other tools and in other environments. I once interviewed for a position as a perl developer and they handed me a written test about (I found out later) very typical perl functionality that I'd never used. I failed miserably and didn't get the job. It happens. Didn't mean I wasn't a good programmer or that I didn't know perl, just meant I didn't use it the same way the folks at that company did.

So it goes. --Kurt Vonnegut

Man... Last year I was interviewed by JPMorgan to work with them (again), In the interview this guy asks (how do you get the RedHat logs for analysis, which one is the tool for that) , of course I couldn't remember it, then he says; "well, seems like you don't know Linux because that's a thing every Linux administrator MUST know", I just told him (ok, ty and left the room of the interview).


That's the thing, I never got a degree, I've been working on this just learning by myself, when I have a Linux problem I just go around and read, try-error things, understand and solve. Seems like having certain level of education would get me better jobs no because the skills for the position require me to know all of that stuff but because the tests are designed in a generic way.

I've recently started a career (I'm 32 now) but I won't which doesn't cover any of that, but I guess it will help me in other tech fields. I think just a degree opens doors, no matter if you really have knowledge or not.

I'll take your advice and start reading and maybe complementing with some courses of programming in coursera or that sort of sites.


True, totally agree, reading is the way to solve many things and of course try-error in some cases (when you can do that).

Who else had never heard of "cp -b", looked it up, and said "ooooohhh"... ?

Addressing your original question, as to what courses there are to start learning some of this.

For all, you should determine if you wish to know more about each major subject area:
AWS:
Seems you do not know AWS. I cannot recommend anything there except some immersion. I know of no real instruction for it, but actually have worked with it via immersion. It wasn't bad.

General programming:
Unsure what your experience level here is. I think if you really do wish to know it, then I'd recommend formal instruction, be that online or attending a class, but something with an instructor. Take one course, determine where you fit. I.e. if you are a pure beginner, or if you need additional knowledge. Then determine how far you wish to take it.

If they and you are talking about scripting and you have experience, along with some idea about how to design sorts, filters, etc, then you seem to know some languages. If you feel you need to learn the subject matter better, there is practice or formal instruction. Once again, it's really about how far you wish to take it. Think how you came to know perl, python, and shell, expand on however you acquired knowledge there.

Linux:
Immersion, and I feel you know it pretty well. Same as my comment about perl, python, and shell. You've learned a lot about it, how'd you do that, and if you feel you can learn more, expand upon your efforts.

There does become a point where it will be not worth your time to take formalized instruction about a thing. Like I've done C for 25+ years. Sure I don't know lots about the language, but I do not feel there are perfect classes which could address the learning points that I might benefit from. In my case, there, I'd benefit by having a pure, and unbiased, expert tutor/resource whom I could ping when I have questions. That doesn't exist, the problem likely would be bias. So I use the web, and continue to form my own biases.

But that's part of my point. You do not seem incompetent, so if you feel you can benefit by brushing up on stuff, then do so, likely with practice and using the web. If there's an actual major subject area you feel you could acquire, try some self exploration and consider if there are any formal courses, but also consider their worth to you.

I have no idea what the -b switch does. Don't care, not looking it up. If I get disqualified for a job because I don't know one command or one command option, so be it and I'm pretty sure I gained a negative opinion about that workplace. Meanwhile it sometimes is a "who knows?" result about a rejection. We all have stories, not bothering to type mine, they'll bore many, etc.

That's an extremely stupid question. Not only, as you already said, would it be enough to look it up in a manpage but also because it's some GNU specific switch not specified in POSIX https://pubs.opengroup.org/onlinepub...lities/cp.html. It doesn't work on Busybox for example.

Indeed, that question was bizarre given the level of the other questions asked. Must be someone's favourite gnu cp flag or something. I've never used that one in over 25 years, and now I'm aware of its existence, I'll still never use it.


As a sysadmin one should be aware of /etc/services, but I've worked with many sysadms who couldn't even string an hello world together in anything other than shell-script and who would just give you a blank stare if you asked about polymorphism.

FWIW, from your list you have experience of a lot of topics that I've not even touched on (I probably have a lot of experience of stuff you've never touched either), and I don't consider either of us monkeys. No one knows it all.

Short answer, employers never get everything they ask for and they don't expect you to be able to answer it all.

Thank you, the thing is my whole career I've been doing what the companies wanted me to do, I mean, I became good at anything the companies would need, because I like technology and Linux ofc there was not a plan on how to build my career path, I'm a kind of "wildcard" with good Linux background, here are some of the technologies and things I usually use/used:

* Creating REST APIS con Flask, Python, JINJA2, Bootstrap, MongoDB
* Bash Scripting
* Web desing/debugging (Firefox/Chrome)
* Jenkins, GIT, Bash, PHP, Python, Debian Packages, Apache Web Server, NetworkManager
* !m "No Machine"
* Ansible
* CUPS // PPD support
* Automation in pipelines with Jenkins, python, Oracle SOA & OSB
* NCOMPUTING Administration.
* OVM Administration
* RHEL, OEL, Debian, Suse, Ubuntu Administration
* Apache HTTP, Tomcat, Jboss/FUSE, Weblogic, Oracle Colaboration Suite, OpenVPN
* Windows Server 2003, Windows Server 2008, Windows XP/Vista/7/8/10
* Wordpress, Sugar CRM, Joomla
* Samba 3 & 4, Postfix, Courier SMTP, Bacula, OpenLDAP, Nagios, Mantis, NTPD, Bind9, Fusion Directory
* GIT, SVN, Jenkins / Hudson
* XEN, KVM
* among many others...

The thing of being a "wildcard" is that some companies do not take me seriously, I can pick up any technology and build things or solve problems, my whole career has been like this, so being rejected because of "some theory" makes me a little sad, so I guess is time to selecting one thing to become better instead of being a "generalist", who knows.

I started working without knowing a bit of Linux back in 2011, they hired me and I learnt and became one of the sysadmins of the company after two years (maybe I'm slow at learning but quite proactive).

I'm learning about Big Data and Data Science right now, but I guess in order to be "relevant" for the market then I'll go for AWS.

I've been rejected many times for that kind of questions, but this one made my day.


I've never used it, it's a new thing for me but once you tell me you have a problem and I read about it I'll learn, that's how I take Linux, one problem at a time, I'm not too immersive in all the things it has unless a problem appears, but I guess some Linux course would be good to know "the most important" things to consider, it could get me a lot of value.

Thank you, everyone, for your answers and sorry for my English level, as you should have guessed I learned it by myself.

You've excellent experience, IMO.

I've told this story before, sorry. I've been hired on at least two occasions because I did have a breadth of experience rather than directly related experience to the job. In neither case was I familiar with, or even aware of the language or tool I was being hired to use/work with. In one case, I'd never even seen the hardware or OS before.

The factor in both cases was that there weren't many (or any) candidates for the positions because the language/tool was fairly new. The first time that happened, after I developed some proficiency with the language and environment, I worked as an "expert" with them for 24 years (!) at 3 different companies.

My point is that you don't need to know everything...and sometimes you don't even need to know anything
Hang in there!

First and foremost, you do have a great deal of excellent experience.

Further, doing all the needed things is something which should be appreciated, and is with most places I've worked at. So don't stop that, but make sure you are somewhere where they appreciate the honest efforts.

I don't like working for companies who feel the need to hold me up to a standard about an obtuse command.

I do not like working in to "tight" of an environment. Sounds like you're the same.

All I can say is get your resume out there and look for new opportunities.

I don't know if you do or don't have a degree, might have missed it, and not asking really. All I can say is that it does help.

I'm actually considering a second degree, for my career, and I got my bachelor's in '89. You do what you need to do is the reality wrt one's career.

Do you mean master's degree? I see that many companies require at least master's degree in their job postings.