Linux Interview General Questions with Answers

What is the difference between soft link and hard link?

1. Using this only a link to the original file is created (shortcut).
2. The size of created shortcut is null.
3. If you delete the file then the created link (shortcut) won't work.
4. In case you delete the shortcut link then it won't affect the original file

How to find the bit size of your linux machine?

# uname -m
i686

# uname -m
x86_64
If you get i386, i586 and i686 in your reply than that signifies your machine is 32-bit but if you get x86_64 or ia64 then your machine will be 64-bit.
# getconf LONG_BIT
32

# getconf LONG_BIT
64Here you will get an output of bit size either 32 or 64.

How can you add a banner or login message in Linux?
By editing these two files
/etc/issue
/etc/motd

For more details follow below link
Add a Banner to your Linux machine

How will you check the release version of your Linux machine?
# cat /etc/redhat-release
What is the difference between normal kernel and kernel-PAE?
kernel in 32 bit machine supports max of 4 GB RAM whereas

kernel PAE in 32 bit linux machine supports till 64 GB RAM

Tell me the command to find all the commands in your linux machine having only 2 words like ls, cp, cd etc.
# find /bin /sbin/usr/bin /usr/sbin -name ?? -type f
Which file is generally used to configure kickstart?
anaconda.cfg

What is the command use to compress a dir using gzip compression?
# tar -czvf myfil.tar.gzip orig_file
What is the command use to compress a dir using bzip2 compression?
# tar -cjvf myfil.tar.bzip2 orig_file
Which log file will you check for all authentication related messages?
/var/log/secure

What is the command to create multiple directories using one command?
Using -p argument along with mkdir command

Which command would you prefer to monitor your system performance and why?
I personally prefer top and sar command to view the performance related factors of my Linux machine.

The top program provides a dynamic real-time view of a running system. It can display system summary information as well as a list of tasks currently being managed by the Linux kernel.

Also sar gives us a standard o/p of the running activity performance related factors in relation to paging, NIC, CPU, Memory etc

For more information on top and sar command follow the below links

Tutorial for Monitoring Tools SAR and KSAR with examples in Linux

What is the command used to find the process responsible for a particular running file?
# fuser filename
# lsof filename
What is the command to take remote of any Linux machine?
# rdekstop
What are the three values shown in load average section of top command?
It shows the current, 5 min back and 15 min back load average value

How to check all the process running by a particular user?
# ps -u username
What is an orphan process?
An orphan process is a process that is still executing, but whose parent has died.

What is a defunct process?
These are also termed as zombie process. These are those process who have completed their execution but still has an entry in the process table. When a process ends, all of the memory and resources associated with it are de-allocated so they can be used by other processes.After the zombie is removed, its process identifier (PID) and entry in the process table can then be reused.

Zombies can be identified in the output from the Unix ps command by the presence of a "Z" in the "STAT" column

What is the command in sar to monitor NIC devices received/transmitted packets?
# sar -n DEV 1 5 

This will show 5 consecutive output each with a time interval of 1 sec for all the ethernet devices

To learn more about SAR command follow the below link
Tutorial for Monitoring Tools SAR and KSAR with examples in Linux