Have you ever thought what happens behind the doors when a user login happens in Linux? Where is the login information for a user is kept in Linux and how the validation of user credential takes place? Well, if not, then I would suggest you to read on as in this article we will discuss how user login management and validation takes place in Linux.
The /etc/passwd file Well, this is the file in Linux system that contains all the relevant information related to user login. If we peek inside this file, this is what it looks like on my Linux... [More]
Most of the people who use Linux on regular basis tend to use command line a lot. This is because once you get used to it, its very easy to do stuff from command line. Now, if a person spends most of his/her time on command line then he/she should start learning all the available short cuts, tips and tricks that Linux command line has to offer. This will not only save time but will also make command line experience interesting. In this article, I will list out a few tricks that I use on regular basis.
Linux command line tips and tricks ... [More]
Does you job requires you to frequently search for patterns in files through Linux command line? Or, do you feel frustrated when you have to open files in UI editors to search for strings or patterns on Linux? Well, if yes then the Linux grep command is for you. This command can be used to search a pattern in one or more files directly from the command line.
In this article, we will understand the usage of Linux grep command through practical examples.
SYNTAX Before jumping on to the examples, lets first take a look on how to use the... [More]
Any application running on Linux may request services like :
Inter process communication I/O services Creating a new process Accessing system hardware etc
Note: The above list is not exhaustive.
The services listed above are all handled by Linux kernel. So, any application in Linux that requires any of these services has to request the Linux kernel to handle the request on its behalf. The request is handed over to kernel by calling corresponding system calls. System calls act as an interface between application and kernel.
A few days back, I was trying to find details of a specific type of files on my Ubuntu box in office. Here is what I was trying to do : find ./ -name "*.out" | xargs ls -lart As you can see that I was trying to list out the details of all the files having .out extension. So far so good as I got what I wanted. Then one of my colleague wanted to use the same command on his Linux machine so he asked me to copy and send it to him. Though copying from command line using mouse and keyboard is not that difficult but somehow after I... [More]
Have you ever got stuck in a situation where-in you opened and edited a file in vim editor but when you tried to save the changes then the following error was thrown by vim : E45: 'readonly' option is set (add ! to override) Well, I encountered this error quite frequently as I usually forget to do a 'sudo' while opening files that require root permissions for editing. Those who have experienced this issue might know how annoying it may get. I have recently found the solution to it so I thought to share it here. The problem Consider... [More]
(Written by Ping Lee, Henry Chuang, Charlotte Yaou, Winson Chao, and Gary Hsueh) Prerequisites To get the most from the article, you should have a basic knowledge of SNORT, Linux and a working Linux system on which you can practice the commands covered in this article. Also you should have some networking knowledge such as TCP/IP, iptables, etc. What Is IPS (Intrusion Prevention System)? Intrusion Detection System (IDS) is a device which monitors packets on your network. IDS reports attack behaviors based on security rules and signatures... [More]
The Linux command 'stat' is used for displaying status information of Linux files and file systems. In this article, we will discuss the usage of stat command with examples.
stat command syntax
The syntax of stat command is :
stat [OPTION]... FILE...
stat command examples
1. A basic example
In the simplest form, the stat command can be used by supplying a file name as an argument :
$ stat testdisk.log
Size: 1014 Blocks: 8 IO Block: 4096 regular file
Device: 805h/2053d Inode:... [More]
In order to better serve our community we would like your input in our first ever Real World Linux survey. It will just take a few minutes and your answers are completely anonymous. This will cover what information interests you and what mechanisms you would like to notify you of updates. If you have problems with the embedded form, you can go to this external link . We appreciate your participation. As a side note, this survey uses the free and open LimeSurvey package running on a Linux server. iframes are not available for you. Please try... [More]
I was on Youtube searching for a tutorial on some open source software and I stumbled upon this Linux/Opensource commercial. I found this one minute video so cute that I decided to share it with you all through this blog. I hope everybody will simply love it. The video Note : The credits for the video goes to the author. The Intention is to just share the information through this video.
In one of the earlier articles at this blog ( here ), we learned the Linux user login management. The article explained how user login and password are managed in Linux. Continuing on the same lines. In this article, we will learn how users are managed in Linux. This article will try to cover basics of Linux user management through command line tools as well as through GUI. Note that since I work on Linux Mint so the GUI part would be applicable only to the Linux debain distributions. Command Line tools for Linux user / group management ... [More]
The netstat command in Linux is a very useful tool when dealing with networking issues. This command is capable of producing information related to network connections, routing tables, interface statistics etc. This utility also helps the network administrators to keep an eye on the invalid or suspicious network connections. In this article we will understand the basics of this command using some practical examples.
The syntax of this command is :
netstat [options]... 1. Display routing information maintained by kernel This... [More]
I've used Ubuntu for a while for my main Linux box, but for some reason Oneiric Ocelot had refused to install on my son's cheap eMachines, so I used Linux Mint for his. It's been OK. It seems simpler than Ubuntu, but the real improvement came when I ended up switching to Cinnamon desktop. I liked Cinnamon so much I ended up switching to it on my Ubuntu box. Alas, it seems the days of Gnome might be over?
C provides a suite of functions ,to provide robust and concrete dynamic memory allocation, namely malloc, realloc, calloc and free. Malloc void * malloc ( size_t size ); size: The number of bytes you wish to allocate. Malloc allocates a block of memory and returns a void pointer to the start of that memory location. If the function failed to allocate the requested block of memory, a null pointer is returned. When you malloc a block, it actually allocates a bit more memory than you asked for. This extra memory is used to store information such... [More]
Introduction Typically, when the operating system is deployed it uses a generic configuration in order to provide a fair performance for any kind of application. The term application, in this paper, is used to reference any software that is executed over the operating system. Therefore, databases, web servers, e-mail servers, in-house made softwares, etc, all of them are referred here by the generic term “application”. The behavior of each application depends on how it was designed and developed, but also on how it is used. At the end, the... [More]