Have you ever thought that how can you run a standard command line utility(for example : ‘cp’) from any directory in the shell irrespective of it’s presence in that directory? How does the shell know where the executable is present and whether it is present at all?
(more…)

I have recently installed Ubuntu 12.04 LTS on my laptop. The first surprise that I got was in the form of the new unity GUI. Anyway, that’s a different story. Other thing that bothered me after sometime was the Ubuntu command line prompt colour. The concern was that while analysing problems where I had to go through lots of data on command line, I was many time lost as to where the output began.
(more…)

With growing number of computers on internet coupled with the ever increasing world of crackers (the so called bad guys of internet), the probability of a computer system being intruded is very high. A recent example of computer system intrusion is the popular attacks of the groups like anonymous into the government websites of USA. The crackers might have their own reasons for these attacks but the reality is that not every cracker is doing this for a cause.
(more…)

Linux today is the fastest growing operating system that is replacing it’s competitors in almost every sphere of technology field. The major reason for this is the simplicity and robustness of this operating system. Besides, there is another quality in Linux that makes it favourite of many. This quality is the seamless customization that can be done with every aspect of this OS. One of the very important aspect is the Linux security. There are many protections and inbuilt security mechanisms that Linux incorporates in the name of system and network security. One of the inbuilt security mechanism is the Linux firewall. Linux provides a very flexible and powerful mechanism to customize the firewall. This mechanism is the Linux IPtables.
(more…)

The Linux free command is used to display the amount of used and free memory in Linux system. This command deals with the physical memory, swap memory and the memory buffers used by Linux kernel. In this article, we will discuss the Linux free command through some practical examples.
(more…)

How Linux is Built ? This is a common question that pops up in mind of those who are new to Linux. Well, I recently found a video on YouTube that explains the basics of how Linux is built. The video talks not only about the Linux developement but also some eye-opening statistics on how rapidly Linux is changing the digital world around us.
(more…)

The other day I was installing Ubuntu 12.04 LTS from a boot-able pen drive. Everything went smooth as Ubuntu was easily able to detect that my system is dual booted with Microsoft Windows XP Professional. It suggested me to overwrite or upgrade the existing Ubuntu (Linux Mint that I was using earlier). I went ahead with overwriting the existing Linux mint.
(more…)

Most of the C projects are not single file projects. The code is spread over tens or hundreds of files. Now suppose there is a situation where you have declared and defined a variable in one file (say file1) and want to use the same variable in other file (say file2) by just telling the compiler that this variable is already defined somewhere else. What would you do? Well, this can be done through the concept of extern variables in c.
(more…)

Till now we have read that there are separate functions (unlink and rmdir) to delete files and directories in Linux. In this article, we will understand Linux remove function that is capable of deleting both files and directories in Linux.
(more…)

In our last article on unlink() function here, we discussed how this function can be used to delete files. Also, this function has a limitation that it cannot be used to delete directories. Here in this article, we will discuss the Linux rmdir function. As the name suggests this function is used to delete directories in Linux.
(more…)