Unix Operating System Tutorials

UNIX operating system articles, tutorials and resources
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lsof or LiS Open Files is a very powerful command available on most of Unix-like systems, it lists all open files (in *nix everything is a file, drives, sockets, inodes, etc.). The listing can filtered using various parameters like process id, owner of the process, etc. In this article we'll...
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tee command is common on Unix like systems and on Windows PowerShell. The tee command writes the input to the file specified and also to the standard output, it was named after the plumbing T-splitter used. Here's a graphical presentation of the tee command: ...
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Now let us try to do same in Unix as we have discussed in the following Article - Splitting String Using Delimiter in Oracle In Unix it is pretty simple. We can use below commands to split echo "GO 4 EXPERT|99999|20130101|20131231"|cut -f1 -d"|" or echo "GO 4...
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Normally web traffic (HTTP) is unencrypted i.e. it's passed around the network in plain text, so anyone with the right tools can view what's being transmitted. This is okay generally, but when we pass sensitive information like credit card information, passwords, nowadays even personal information...
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The GNU/Linux screen program is quite unknown, except for geeks & *nix experts, it helps you create multiple terminal sessions from a single one and lets you detach from the screen, at the same time maintaining the sessions as if you had never left the session and you can attach/connect to the...
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du is an abbreviation for (Disk Usage), this command calculates & returns the size of entire directory tree as well as of individual files. df is an abbreviation for (Disk Free), it's job is to calculate and return the amount of free space of a disk/partition. These two commands report space...
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xargs is an utility which is used to build & execute command-lines. xargs reads from the standard input (STDIN) space, tab, newline & end-of-file (EOF) delimited strings and executes the specified utility with the strings as argument(s). Most utilities/systems have a limit on the maximum no. of...
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Netcat (also known as ‘nc’ or ‘Swiss Army knife’) is a networking utility used for reading or writing from TCP and UDP sockets using an easy interface. NetCat is designed as a Dependable ‘back-end’ device that can be used directly or easily driven by other programs and scripts. Netcat is a treat to...
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What Unix / Linux File Permission is? Every File or directory in the Linux Operating system has an access level which specifies the group or the users can actually access it. Linux Provides us with mainly 3 access levels for each user group i.e. Read , Write and Execute. These permissions can be...
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There are times, when sitting on your Linux box, working on a command line terminal, you suddenly feel a need of copying a file to/from a remote host. At this point you desire a command line utility that could do this task for you in just one line. Well, this is where 'scp' saves your day :-) ...
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Byte ordering in memory refers to the way in which the bytes corresponding to a certain value is stored in the memory. There are two ways in which bytes are stored in memory : Big endian Little endian Lets understand them one by one : Big endian
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Cron is a Unix/Linux etc .. utility thaat allows the tasks to be run at specific time as well as at specific intervals..The job that the program does are know as CronJobs and are stored in a table (Cron Table).. Using To schedule any task with cron we can use crontab command in Unix.. Lets...
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You might have studied various mechanisms through which two processes interact on same host. For example message queues, shared memory etc. But what about interaction between two process running on two different hosts (lets say on a LAN or WAN). Here comes the concept of network programming where...
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This is continuation of my previous articles .. Please don't miss them :- Bash Simple Tricks Bash Simple Tricks (continuation) Again I am following a question – solution approach to demonstrate my scripts.. Scripts
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Regular expressions commonly known as ‘regex’ provide an abstract and Flexible means to compare strings. It’s mainly used for scrapping and extraction of useful data from strings. In this tutorial we’ll be looking at some regular expressions using grep in Unix/Linux and how to use them in...
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SSH is a abbreviation for Secure Shell is a network protocol that allows data-exchange between devices on the network..This is mainly used in linux OS's to access shell accounts , shell commands etc... SSH was mainly designed as a replacement modification to telnet etc..other insecure remote shells...
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As the title suggests it is continuation of Basics of CrackMe With Sample and Example. I assume a working knowledge of GDB and ASM as basics. In this article we'll be cracking a simple application that is more advanced to the previous one.. In this article I take the cracking a step further by...
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This is continuation of my previous article - Bash Simple Tricks Tutorial Again I am following a question – solution approach to demonstrate my scripts.. Scripts Write a script that displays the number of lines in a file that starts with a or A Script :-
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1. What Is Kernel? A kernel is a central component of an operating system. It acts as an interface between the user applications and the hardware. The sole aim of the kernel is to manage the communication between the software (user level applications) and the hardware (CPU, disk memory etc). The...
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In this tutorial of mine I am demonstrating some bash commands with some example scenarios/questions and their solutions.... What is Bash:- Bash or Bourne Again Shell is a reimplementation of Bourne shell... Bash is the default shell that comes with most of the linux distributions out...
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