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?