{"id":22722,"date":"2021-07-24T20:03:21","date_gmt":"2021-07-24T20:03:21","guid":{"rendered":"https:\/\/www.devopsschool.com\/blog\/?p=22722"},"modified":"2021-07-24T20:03:24","modified_gmt":"2021-07-24T20:03:24","slug":"interview-questions-answers-complete-guide-for-linux","status":"publish","type":"post","link":"https:\/\/www.devopsschool.com\/blog\/interview-questions-answers-complete-guide-for-linux\/","title":{"rendered":"Interview Questions &#038; Answers Complete Guide for Linux"},"content":{"rendered":"\n<h1 class=\"wp-block-heading\">Linux<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">What is your experience with Linux?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain what each of the following commands does and give an example on how to use it:<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain each field in the output of <code>ls -l<\/code> command<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What are hidden files\/directories? How to list them?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain what each of the following commands does and give an example on how to use it:<\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>sed<\/li><li>grep<\/li><li>cut<\/li><li>awk<\/li><\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">What each of the following commands does?<\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>pwd<\/li><li>cd<\/li><li>find<\/li><li>ls<\/li><\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">What each of the following commands does?<\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>cd \/<\/li><li>cd ~<\/li><li>cd<\/li><li>cd ..<\/li><li>cd .<\/li><li>cd &#8211;<\/li><\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">How to rename the name of a file or a directory?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Specify which command would you use (and how) for each of the following scenarios<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Remove a directory with files<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Display the content of a file<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Provides access to the file \/tmp\/x for everyone<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Change working directory to user home directory<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Replace every occurrence of the word &#8220;good&#8221; with &#8220;great&#8221; in the file \/tmp\/y<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How can you check what is the path of a certain command?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain redirection<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain piping. How do you perform piping?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Fix the following commands:<\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>sed &#8220;s\/1\/2\/g&#8217; \/tmp\/myFile<br>= find . -iname *.yaml -exec sed -i &#8220;s\/1\/2\/g&#8221; {} ;<\/li><\/ul>\n\n\n\n<h1 class=\"wp-block-heading\">Linux FHS<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">In Linux FHS (Filesystem Hierarchy Standard) what is the \/?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is stored in each of the following paths?<\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>\/bin, \/sbin, \/usr\/bin and \/usr\/sbin<\/li><li>\/etc<\/li><li>\/home<\/li><li>\/var<\/li><li>\/tmp<\/li><\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">What is special about the \/tmp directory when compared to other directories?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What kind of information one can find in \/proc?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Can you create files in \/proc?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">In which path can you find the system devices (e.g. block storage)?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Running the command df you get &#8220;command not found&#8221;. What could be wrong and how to fix it?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How do you schedule tasks periodically?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to check which commands you executed in the past?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Permissions<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">How to change the permissions of a file?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What does the following permissions mean?:<\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>777<\/li><li>644<\/li><li>750<\/li><\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">What this command does? chmod +x some_file<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain what is setgid and setuid<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is the purpose of sticky bit?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What the following commands do?<\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>chmod<\/li><li>chown<\/li><li>chgrp<\/li><\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">What is sudo? How do you set it up?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">True or False? In order to install packages on the system one must be the root user or use the sudo command<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain what are ACLs. For what use cases would you recommend to use them?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">You try to create a file but it fails. Name at least three different reason as to why it could happen<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Shell Scripting<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">What this line in scripts mean?: #!\/bin\/bash<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">True or False?: when a certain command\/line fails, the script, by default, will exit and will no keep running<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain what would be the result of each command:<\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>echo $0<\/li><li>echo $?<\/li><li>echo $$<\/li><li>echo $@<\/li><li>echo $#<\/li><\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">How do you debug shell scripts?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How do you get input from the user in shell scripts?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain continue and break. When do you use them if at all?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to store the output of a command in a variable?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How do you check variable length?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Can you give an example to some Bash best practices?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is the ternary operator? How do you use it in bash?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What does the following code do and when would you use it?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">diff &lt;(ls \/tmp) &lt;(ls \/var\/tmp)<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux systemd<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">What is systemd?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">On a system which uses systemd, how would you display the logs?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Describe how to make a certain process\/app a service<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Debugging<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Where system logs are located?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to follow file&#8217;s content as it being appended without opening the file every time?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What are you using for troubleshooting and debugging network issues?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What are you using for troubleshooting and debugging disk &amp; file system issues?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What are you using for troubleshooting and debugging process issues?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What are you using for debugging CPU related issues?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">You get a call from someone claiming &#8220;my system is SLOW&#8221;. What do you do?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain iostat output<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to debug binaries?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is the difference between CPU load and utilization?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How you measure time execution of a program?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Kernel<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">What is a kernel, and what does it do?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How do you find out which Kernel version your system is using?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is a Linux kernel module and how do you load a new module?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain user space vs. kernel space<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What are system calls? What system calls are you familiar with?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Virtualization<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">What virtualization solutions are available for Linux?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is KVM?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux SSH<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">What is SSH? How to check if a Linux server is running SSH?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Why SSH is considered better than telnet?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is stored in ~\/.ssh\/known_hosts?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is the difference between SSH and SSL?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What ssh-keygen is used for?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is SSH port forwarding?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux &#8211; Globbing, Wildcards<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">What is Globbing?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What are wildcards? Can you give an example of how to use them?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain what will ls [XYZ] match<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain what will ls [^XYZ] match<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain what will ls [0-5] match<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What each of the following matches<\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>?<\/li><li>*<\/li><\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">What do we grep for in each of the following commands?:<\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>grep &#8216;[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}&#8217; some_file<\/li><li>grep -E &#8220;error|failure&#8221; some_file<\/li><li>grep &#8216;[0-9]$&#8217; some_file<\/li><\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Which line numbers will be printed when running <code>grep '\\baaa\\b'<\/code> on the following content:<\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>aaa bbb ccc.aaa aaaaaa<\/li><\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">What is the difference single and double quotes?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is escaping? What escape character is used for escaping?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is an exit code? What exit codes are you familiar with?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Boot Process<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Tell me everything you know about the Linux boot process<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is GRUB2?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is Secure Boot?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What can you find in \/boot?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Disk &amp; Filesystem<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">What&#8217;s an inode?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Which of the following is not included in inode:<\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>Link count<\/li><li>File size<\/li><li>File name<\/li><li>File timestamp<\/li><\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">How to check which disks are currently mounted?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">You run the mount command but you get no output. How would you check what mounts you have on your system?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is the difference between a soft link and hard link?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">True or False? You can create an hard link for a directory<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">True or False? You can create a soft link between different filesystems<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What happens when you delete the original file in case of soft link and hard link?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Can you check what type of filesystem is used in \/home?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is a swap partition? What is it used for?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to create a new empty file<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How would you check what is the size of a certain directory?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is LVM?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain the following in regards to LVM:<\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>PV<\/li><li>VG<\/li><li>LV<\/li><\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">What is NFS? What is it used for?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What RAID is used for? Can you explain the differences between RAID 0, 1, 5 and 10?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Describe the process of extending a filesystem disk space<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is lazy umount?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is tmpfs?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is stored in each of the following logs?<\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>\/var\/log\/messages<\/li><li>\/var\/log\/boot.log<\/li><\/ul>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Performance Analysis<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">How to check what is the current load average?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">You know how to see the load average, great. but what each part of it means? for example 1.43, 2.34, 2.78<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to check process usage?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to check disk I\/O?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to check how much free memory a system has? How to check memory consumption by each process?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to check TCP stats?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Processes<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">how to list all the processes running in your system?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to run a process in the background and why to do that in the first place?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How can you find how much memory a specific process consumes?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What signal is used by default when you run &#8216;kill <em>process id<\/em>&#8216;?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What signals are you familiar with?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What kill 0 does?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What kill -0 does?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is a trap?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Every couple of days, a certain process stops running. How can you look into why it&#8217;s happening?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What happens when you press ctrl + c?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is a Daemon in Linux?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What are the possible states of a process in Linux?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How do you kill a process in D state?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is a zombie process?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to get rid of zombie processes?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to find all the<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Processes executed\/owned by a certain user<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Process which are Java processes<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Zombie Processes<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is the init process?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Can you describe how processes are being created?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to change the priority of a process? Why would you want to do that?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Can you explain how network process\/connection is established and how it&#8217;s terminated?&gt;<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What strace does? What about ltrace?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Find all the files which end with &#8216;.yml&#8217; and replace the number 1 in 2 in each file<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">You run ls and you get &#8220;\/lib\/ld-linux-armhf.so.3 no such file or directory&#8221;. What is the problem?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How would you split a 50 lines file into 2 files of 25 lines each?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is a file descriptor? What file descriptors are you familiar with?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is NTP? What is it used for?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain Kernel OOM<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Security<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">What is chroot? In what scenarios would you consider using it?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is SELiunx?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is Kerberos?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is nftables?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What firewalld daemon is responsible for?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Do you have experience with hardening servers? Can you describe the process?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Networking<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">How to list all the interfaces?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is the loopback (lo) interface?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What the following commands are used for?<\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>ip addr<\/li><li>ip route<\/li><li>ip link<\/li><li>ping<\/li><li>netstat<\/li><li>traceroute<\/li><\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">What is a network namespace? What is it used for?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to check if a certain port is being used?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How can you turn your Linux server into a router?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is a virtual IP? In what situation would you use it?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">True or False? The MAC address of an interface is assigned\/set by the OS<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Can you have more than one default gateway in a given system?<\/h3>\n\n\n\n<p>Which port is used in each of the following protocols?:<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>SSH<\/li><li>SMTP<\/li><li>HTTP<\/li><li>DNS<\/li><li>HTTPS<\/li><\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">What is telnet and why is it a bad idea to use it in production? (or at all)<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is the routing table? How do you view it?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How can you send an HTTP request from your shell?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What are packet sniffers? Have you used one in the past? If yes, which packet sniffers have you used and for what purpose?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to list active connections?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to trigger neighbor discovery in IPv6?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is network interface bonding and do you know how it&#8217;s performed in Linux?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What network bonding modes are there?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is a bridge? How it&#8217;s added in Linux OS?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux DNS<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">How to check what is the hostname of the system?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What the file \/etc\/resolv.conf is used for? What does it include?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What commands are you using for performing DNS queries (or troubleshoot DNS related issues)?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Packaging<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Do you have experience with packaging? (as in building packages) Can you explain how does it works?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How packages installation\/removal is performed on the distribution you are using?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">RPM: explain the spec format (what it should and can include)<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How do you list the content of a package without actually installing it?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to know to which package a file on the system belongs to? Is it a problem if it doesn&#8217;t belongs to any package?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Where repositories are stored? (based on the distribution you are using)<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is an archive? How do you create one in Linux?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to extract the content of an archive?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Why do we need package managers? Why not simply creating archives and publish them?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux DNF<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">How to look for a package that provides the command \/usr\/bin\/git? (the package isn&#8217;t necessarily installed)<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Linux Applications and Services<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What can you find in \/etc\/services?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to make sure a Service starts automatically after a reboot or crash?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">You run ssh 127.0.0.1 but it fails with &#8220;connection refused&#8221;. What could be the problem?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to print the shared libraries required by a certain program? What is it useful for?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is CUPS?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What types of web servers are you familiar with?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Users and Groups<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">What is a &#8220;superuser&#8221; (or root user)? How is it different from regular users?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How do you create users? Where user information is stored?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Which file stores information about groups?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How do you change\/set the password of a user?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Which file stores users passwords? Is it visible for everyone?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Do you know how to create a new user without using adduser\/useradd command?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What information is stored in \/etc\/passwd? explain each field<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to add a new user to the system without providing him the ability to log-in into the system?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to switch to another user? How to switch to the root user?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is the UID the root user? What about a regular user?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What can you do if you lost\/forogt the root password?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is \/etc\/skel?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to see a list of who logged-in to the system?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain what each of the following commands does:<\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>useradd<\/li><li>usermod<\/li><li>whoami<\/li><li>id<\/li><\/ul>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Hardware<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Where can you find information on the processor?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How can you print information on the BIOS, motherboard, processor and RAM?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How can you print all the information on connected block devices in your system?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux &#8211; Random<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Give 5 commands which are two letters long<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What ways are there for creating a new empty file?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How <code>cd -<\/code> works? How does it knows the previous location?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">List three ways to print all the files in the current directory<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to count the number of lines in a file? What about words?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">You define x=2 in \/etc\/bashrc and x=6 ~\/.bashrc you then login to the system. What would be the value of x?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is the difference between man and info?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain &#8220;environment variables&#8221;. How do you list all environment variables?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to create your own environment variables?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What a double dash (&#8211;) mean?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux &#8211; AWK<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">What the awk command does? Have you used it? What for?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to print the 4th column in a file?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to print every line that is longer than 79 characters?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What the lsof command does? Have you used it? What for?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is the difference between find and locate?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">System Calls<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Explain the fork() system call<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain the exec() system call<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What system call is used for listing files?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What system call is used for creating a new process?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What are the differences between exec() and fork()?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Why do we need the wait system call?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What execve() does?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is the return value of malloc?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain the pipe() system call. What does it used for?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What happens when you execute ls -l?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What happens when you execute ls -l *.log?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What readdir() system call does?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What exactly the command alias x=y does?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Filesystem &amp; Files<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">How to create a file of a certain size?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What does the following block do?:<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">open(&#8220;\/my\/file&#8221;) = 5<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">read(5, &#8220;file content&#8221;)<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Describe three different ways to remove a file (or its content)<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is the difference between a process and a thread?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is context switch?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">You found there is a server with high CPU load but you didn&#8217;t find a process with high CPU. How is that possible?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Advanced &#8211; Networking<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">When you run ip a you see there is a device called &#8216;lo&#8217;. What is it and why do we need it?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What the traceroute command does? How does it works?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is network bonding? What types are you familiar with?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">How to link two separate network namespaces so you can ping an interface on one namespace from the second one?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What are cgroups?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain Process Descriptor and Task Structure<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What are the differences between threads and processes?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain Kernel Threads<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What happens when socket system call is used?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">You executed a script and while still running, it got accidentally removed. Is it possible to restore the script while it&#8217;s still running?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Memory<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">What is the difference between MemFree and MemAvailable in \/proc\/meminfo?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is the difference between paging and swapping?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Explain what is OOM killer<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Distribution<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">What is a Linux distribution?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What Linux distributions are you familiar with?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What are the components of a Linux distribution?<\/h3>\n\n\n\n<h1 class=\"wp-block-heading\">Linux Misc<\/h1>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Wildcards are implemented on user or kernel space?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">If I plug a new device into a Linux machine, where on the system, a new device entry\/file will be created?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Why there are different sections in man? What is the difference between the sections?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">What is User-mode Linux?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Linux Nerds<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Under which license Linux is distributed?<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">Linux Master Application<\/h3>\n\n\n\n<h3 class=\"wp-block-heading\">A completely free application for testing your knowledge on Linux<\/h3>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Linux What is your experience with Linux? Explain what each of the following commands does and give an example on how to use it: Explain each field&#8230; <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_joinchat":[],"footnotes":""},"categories":[2],"tags":[],"class_list":["post-22722","post","type-post","status-publish","format-standard","hentry","category-uncategorised"],"_links":{"self":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/22722","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/comments?post=22722"}],"version-history":[{"count":1,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/22722\/revisions"}],"predecessor-version":[{"id":22723,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/22722\/revisions\/22723"}],"wp:attachment":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/media?parent=22722"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/categories?post=22722"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/tags?post=22722"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}