Friday, October 31, 2025
Top 5 Courses to Learn Kali Linux in 2025 - Best of Lot
Kali Linux is an open-source Debian system based on Linux developed by the
offensive security company for ethical hackers. It contains more than 400
tools categorized to make it easy for security researchers to analyze your
network, test the system security, discover different vulnerabilities inside a
web application, hide malware in apps, and target Android phones. If you want
to learn Kali Linux and looking for the best online courses to learn Kali
Linux on your own then you have come to the right place. Earlier, I have
shared the best Ethical Hacking courses
and
Cyber Security Courses, and in his article, I am going to share the best Kali Linux courses for
beginners.
Labels:
courses
,
Cyber Security
,
Kali Linux
,
linux
Monday, October 20, 2025
Top 7 Courses to Learn Shell scripting in Linux (bash, ksh, csh) Online in 2025 - Best of Lot
Hello guys, you might know that a massive chunk of a developer's time is wasted in trying to repeat tasks and commands, especially when it comes to working with a bunch of UNIX or Linux machines, and a good knowledge of shell scripting can free you from such mundane task and give time to do some interesting stuff. If you don't know what shell scripting is then let me tell you is nothing but a program written using shell built-ins, and Linux commands to automate things, like checking if a host is reachable or finding and deleting large files that are older than certain days or archiving them into another machine.
Labels:
courses
,
linux
,
online resources
Wednesday, October 15, 2025
6 Websites to Learn Linux Command Line for FREE - Best of Lot
Hello guys, if you want to learn Linux online and are looking for free resources
to learn Linux commands and concepts, you have come to the right place. Earlier,
I have shared
Linux and shell scripting courses
and
tutorials, and in this article, you will find the best places to learn Linux online. Linux
is one of the most useful skills for Programmers and Developers, and there are a
lot of useful resources on the internet to learn Linux and master Linux command
lines or bash shells. In this article, I will share websites where you can learn
Linux for FREE. I have tried to include a variety of websites like Udemy and
Coursera for online courses, CodeCademy and Educative for online interactive
learning, and Pluralsight as a membership-based website.
Labels:
best of javarevisited
,
linux
,
online resources
Saturday, October 4, 2025
Top 10 UNIX and Linux System Programming Books in 2025 - Best of Lot, Must Read
I have been sharing programming books in this blog for a long time, starting with core Java; I moved to other related technology, like Spring, Design patterns, Data Structure and Algorithms, etc. Today, I am going to share some of the best UNIX and Linux programming books. The list contains some of the must-read UNIX books from great writers like Sir Richard. Stevens, Sir Brain Kernighan, who has contributed so much to the development of the UNIX operating system. Most of the books on this list are timeless, classic, and don't age with time, much like UNIX, which is around for the last 40 years, and I am sure it will be around for the next 40 years, or maybe forever.
Friday, August 1, 2025
Top 20 Linux Interview Questions with Answers for 1 to 3 Years Experienced Developers
Hello guys, if you are preparing for Developer and DevOps interview and
looking for Linux questions for interviews then you have come to the right
place. Earlier, I have shared popular
UNIX Interview questions
and
DevOps Interview Questions
and in this article, I am going to share 20 common Linux questions from
interviews with Answers. These questions covers essential Linux commands like
Linux file system, permission model, Linux commands, shell and kernels etc. If
you have worked in Linux then you can easily answer these questions but if you
have forgot them then you can always join these
best Linux courses
to learn and revise key Linux concepts before interviews.
Labels:
interview questions
,
linux
Thursday, July 31, 2025
10 Example of netstat networking command in UNIX and Linux
The netstat command is one of the most essential and useful networking command for Linux users. It is a general, all purpose network information tool which can be used to find out information about current network connections, multicast group membership, routing tables, network interface statistics and many other low-level details of the host's current network configuration. The good knowledge of netstat command is not only important from the troubleshooting perspective but also from security perspective. It gives useful security related information e.g. what network ports are currently "open" on your system and the list of current network connections and their states.
Wednesday, June 4, 2025
How Long does It take To Learn Linux?
Hello guys, if you want to learn Linux but not sure how to start then you have come to the right place. Earlier, I have shared best places to learn Linux and best Linux books for beginners and Linux interview questions with answers and in this article, I Am going to share the best way to learn Linux and answer frequently asked question, how long does it take to Learn Linux. In general, you can learn Linux in one weekend but it can take weeks before you become a Linux master as there are a lot of Linux commands and concepts to master. In this article, I will answer this question objectively depending upon your goal, for example, for a developer it can take a week to Learn Linux but for System Admin it could be months because they need more in-depth knowledge.
Labels:
best of javarevisited
,
linux
,
programming
Sunday, May 18, 2025
10 Linux Commands and Options Every Developer should Learn
Hello guys, you might have read many articles about popular Linux commands on the internet but this article is a bit different. In this article, I am going to share some lesser-known options of essential Linux commands like find, grep, mkdir, etc, which many Linux users, including programmers, don't know, even after using the command for quite some time. For example, cp -p is an option that I discovered quite late but ever since I discovered it I have been using it regularly as it preserve timestamp and I can see when this file was originally created. I am going to share 10 such Linux command examples in this post, which I am sure you will love it and if you already know them, then there is a good chance that you have something similar to share with us in the comments section.
Labels:
best of javarevisited
,
linux
,
programming
Monday, May 5, 2025
Top 50 Linux Interview Questions Answers for 3 to 5 Years Experienced
Linux is the #1 operating system for hosting real world production application. Most of the real world Java application in big IBs are hosted on RedHat Linux. This makes Linux an extremely important skill for getting a Job. Along with any programming language e.g. Java or C++, you must have good command on Linux and SQL to get a programming job. Btw, Linux is not just limited for development job but it is even more important for support roles and system admin jobs. If you are working in production support then an excellent knowledge of Linux is expected from you, which includes knowing fundamental of Linux e.g. how Linux OS works?, what is kernel or shell?, or what is init process?, as well as good knowledge of various Linux commands to perform day-to-day job, and troubleshoot any production issues.
Labels:
interview questions
,
linux
,
unix
Wednesday, April 16, 2025
10 Examples of SED Command in UNIX and Linux
SED command in UNIX stands for
stream editor and it can perform lots of functions on file like searching,
find and replace, insertion or deletion. Though the most common use of SED command
in UNIX is for a substitution or for find and replace. By using SED you can edit
files even without opening it, which is a much quicker way to find and replace
something in the file, than first opening that file in VI Editor and then changing it.
In this SED command tutorial, we will see some practical examples of SED commands
in UNIX based systems e.g. Linux. I must say having a good grip on the find, grep, sort, vi editors and SED can
take you next level of UNIX and Linux working experience.
Saturday, April 12, 2025
How to Create, Update and Remove Soft link in Linux and UNIX - Example
Symbolic links, Symlink or Soft link in Unix are a very important concept to understand and use in various UNIX operating systems e.g. Linux, Solaris, or IBM AIX. Symlinks give you so much power and flexibility that you can maintain things quite easily. I personally feel that along with find, grep and other UNIX commands, the command to create a soft link and update soft link i.e. ln -s is also a must for anyone working in the UNIX machine. Whenever I do scripting or write any UNIX script I always write for symlinks rather than pointing to the absolute path of directories in UNIX.
Friday, April 11, 2025
10 Examples of chmod command in UNIX Linux
chmod command in UNIX or Linux is used to change file or directory permissions. This is one of many UNIX basic commands which a UNIX or Linux user must be familiar with. In this UNIX command tutorial we will see how to change file permissions using the chmod command, what are file permissions in UNIX, how to change permissions of directory and sub-directory using UNIX chmod command and finally how to create executable files in UNIX using the chmod command. Before going directly into examples of chmod command let's spend a few minutes on understanding file permissions in UNIX and why do we need to change file permissions etc.
Thursday, April 10, 2025
How to close telnet terminal in Linux and Windows (quit, exit not working)? Example
The telnet is one of the most useful Linux networking commands, which is used to check if a server is listening on a particular port and it's whether up and running or not, but it's a little bit tricky to use, especially, if you are not using it on daily basis. Though I have used telnet before, when I use it after a long time, I actually forgot how to close the telnet terminal and how to get out of it. I tried every possible Linux commands I can think of which is used to close, cancel a command, or exit from VIM editor in UNIX, like Ctrl + C, quit, exit, q! and even the escape character '^]', only to realize that nothing is working. It may sound silly that an experienced developer cannot even come out of a telnet terminal but this is a true story.
Wednesday, April 9, 2025
5 Example of sort command in UNIX or Linux - Tutorial
Sorting is one of the essential tasks we always need to perform and UNIX or Linux has great support for sorting by using sort command. No matter what kind of shell script you are writing or you are looking for some information or reports many times you need to sort the output of one command or a set of line, with a combination of the sort with find command and grep in UNIX you can handle support request and report quite easily. In this UNIX sort command tutorial, we will see how we can use sort command in UNIX to achieve our sporting goal. This tutorial contains some of the practical example of sort command for sorting data in UNIX. With the use of “unique” and “sort” command, you can remove duplicates and present a sorted data in UNIX.
Tuesday, April 8, 2025
How to find and kill a Process Listening on a port in Linux? netstat and lsof command examples
In Linux, many times, you want to find out the PID of a process that is listening on a port e.g. if multiple tomcat servers are running on a host and you have to kill that process, but in order to kill that process you need the process id, how do you find the PID of the tomcat listening on port 8080? There are many Linux commands to find the process using a specific port, but I'll share what I use. I always use the netstat command with -p option, which displays the process id of the process listening on a port. Btw, netstat is not the only command to find all processes using a particular port, you can also use the lsof command for the same purpose.
Monday, April 7, 2025
File permissions in UNIX Linux with Example >> Unix Tutorial
Whenever we execute ls command in UNIX you might have observed that it list file name with lot of details e.g.
stock_options:~/test ls -lrt
total 8.0K
-rw-r--r-- 1 stock_options Domain Users 1.1K Jul 15 11:05 sample
If you focus on the first column you will see the file permissions as "-rw-r--r--" this is made of three parts user, group, and others. The user part is permission relate to user logged in, group is for all the members of the group and others is for all others. also each part is made of three permissions read, write and execute so "rw-" means only "read and write" permission and "r--" means read-only permission.
Sunday, April 6, 2025
10 Examples of Vim or VI editor in UNIX and Linux
VI Editor is like notepad in UNIX but it’s extremely powerful and has a sophisticated feature to work as complete IDE. No matter which version of UNIX you are working or which flavor you are using you always find either VI editors or VIM there. VI is a very large topic and I am not covering every aspect of it what I am sharing here is some examples of using VI editor in UNIX or Linux. most of the time we use only 10% of VI editor and never know 90% of it, to be frank, I also don't know many of VI features by heart but I always search for it, see people working in VI and learn from their experience as well.
Labels:
linux
,
unix
,
Vim command
Friday, April 4, 2025
How to set JAVA_HOME environment in Linux, Unix and Windows? Example
JAVA_HOME is a system environment variable that represents the JDK installation directory. When you install JDK in your machine (Windows, Linux, or UNIX) it creates a home directory and puts all its binary (bin), library(lib), and other tools. In order to compile the java program "javac" tool should be in your PATH and in order to get that in PATH we use the JAVA_HOME environment variable. Many tools like ANT and web servers like tomcat use JAVA_HOME to find java binaries. In this article, we will see how to set the JAVA_HOME environment variable in the different operating systems including Windows (Windows 7, Vista, XP) and Linux (Unix).
Tuesday, April 1, 2025
Top 3 Books to Learn TCP/IP, UDP and Computer Networking Protocols - Best of Lot
Both TCP/IP and UDP are very popular networking protocol and in this era of the internet and a connected world, they become even more important. No matter, whether you are a computer science graduate or doing masters in computer science, a software engineer, a network engineer, or a Java programmer, good knowledge of TCP/IP and UDP goes a long way to securing a job and doing well on it. Even though I mostly interview for Java programmers, I almost always ask a couple of questions on TCP/IP and UDP protocol to check if the candidate is familiar with computer network basics or not because even if you work for Java application, you are exposed to the network.
Friday, March 14, 2025
Top 5 Udemy Courses to Learn VI Editor or Vim in Linux in 2025 - Best of Lot
Hello guys, if you want to master the VI editor or Vim and looking for the best online courses then you have come to the right place. Earlier, I have shared the best Linux courses and best shell scripting courses and today, I am going to share the best courses to learn VI editor. If you have worked in Linux, then you may know that VIM is one of the most useful and powerful text editors and every people working in a Linux environment should know about VIM. Also known as VI Editor, it is often touted as the go-to-editor for genius developers who make full use of Vim's capability for code navigation and do fancy things.
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