Linux Interview questions – Part4

In this post, I will share next part of linux interview questions series.

  • What is a tunnel and how you can bypass a http proxy?
  • What is the difference between IDS and IPS?
  • What shortcuts do you use on a regular basis?
  • What is the Linux Standard Base?
  • What is an atomic operation?
  • Your freshly configured http server is not running after a restart, what can you do? Check http server logs to find the errors
  • What kind of keys are in ~/.ssh/authorized_keys and what it is this file used for?
  • I’ve added my public ssh key into authorized_keys but I’m still getting a password prompt, what can be wrong? – check permissions and ownership of authorized file
  • Did you ever create RPM’s, DEB’s or solaris pkg’s?
  • What does :(){ :|:& };: do on your system?
  • How do you catch a Linux signal on a script?
  • Can you catch a SIGKILL?
  • What’s happening when the Linux kernel is starting the OOM killer and how does it choose which process to kill first?
  • Describe the linux boot process with as much detail as possible, starting from when the system is powered on and ending when you get a prompt.
  • What’s a chroot jail?
  • When trying to umount a directory it says it’s busy, how to find out which PID holds the directory?
  • What’s LD_PRELOAD and when it’s used?
  • You ran a binary and nothing happened. How would you debug this?
  • What are cgroups? Can you specify a scenario where you could use them?
  • What are Namespaces, SystemD, JournalD? When do you use each of them?
  • How can you remove/delete a file with file-name consisting of only non-printable/non-type-able characters?
  • How can you increase or decrease the priority of a process in Linux?
  • What are run-levels in Linux?

Difficult Interview question:

  • A running process gets EAGAIN: Resource temporarily unavailable on reading a socket. How can you close this bad socket/file descriptor without killing the process?