Closed source software can be distributed for free or for a cost; either way, the source code for the software is unavailable from the original developers. In Linux, no further organization or formatting is specified for a file. Until Linux came along it was either Windows or Macintosh - take it …

At that time a new generation of computers with proprietary operating systems was introduced, and their vendors required that users sign non-disclosure statements in order to obtain copies of the operating systems. Software running on the CPU must be able to read and write those controlling registers. (To be a …

Open Source software, like its name suggests, provides users with an open code that can be freely used, modified, and shared by everyone. The so-called open source and free software development models started with the Free Software Foundation and were popularized with Linux. Each filesystem is mounted to a specific …

They come in multiple varieties, including the Unix domain socket, which is the form of socket used for communication within the local machine. The GNU C library provides more than its name suggests. The bss section was conceived solely as an optimization for this purpose. Unix systems, however, are dynamic …

As a result of this restriction, artistic licenses are rarely used because many developers do not want to work on potentially futile projects. So, you can focus on the development work and leave other worries aside. The CPU can access both the system space memory and the I/O space …

The price for a Windows license amounts to an average of one fourth of each new computer's price. Many of the devices you own probably, such as Android phones, digital storage devices, personal video recorders, cameras, wearables, and more, also run Linux. Linux systems always have a root filesystem. Again …

(See "Shell Built-in Commands.") Readline has variables that can be used to further customize its behavior. This led to the development of the free software movement by Richard Stallman. If a parent process terminates before its child, the kernel will reparent the child to the init process. The price for …

The text section contains executable code and read-only data, such as constant variables, and is typically marked read-only and executable. At the same time, many executives have a crude interpretation of its value to corporations?"It's free, and therefore it's cheap." Slowly, that mentality is changing, but it's still true …

Block devices are accessed via the buffer cache and may be randomly accessed, that is to say, any block can be read or written no matter where it is on the device. Among the easiest to try at first are the text editors, word processors, image viewers, calculators and games …

Keep in mind that these are only conventions---not rules. You can easily see the exported kernel symbols and their values by looking at /proc/ksyms or by using the ksyms utility. Traditionally, Unix programs have been single-threaded, owing to Unix's historic simplicity, fast process creation times, and robust IPC mechanisms …

For some small business leaders I've consulted, the human factor is either a notion to be rejected or ignored. For most users, LILO works best. Kerneld is just an agent of the kernel, scheduling work on its behalf. Not often are our basic rights thought of in the context of …

Its latest releases often inspire the other Linux distributions to adopt new features and make changes. By then, much of the GNU operating system had been completed, with the notable exception of a kernel (i.e., the core of the operating system). The entire Linux kernel was written from scratch …

You can also press the C key at any time to enter an interactive shell mode, allowing you to submit commands on the fly. Businesses, with no faith in their ability to succeed with Open Source, would resort to writing proprietary software that can be sold on a shelf. The …

Time enough for a soapbox. It could be argued that its smaller number of vulnerabilities is because of its rarer deployment, but the simplest explanation is that OpenBSD has focused strongly on security - and achieved it better than the rest. The BSD socket layer calls the INET layer socket support …

Installation can take a while, depending on the speed of the computer and the options selected. Apart from the ability of a loaded module to crash the operating system by being badly written, it presents another danger. Each approach has its advantages and disadvantages. If your memory is like mine …

If it does not exist, it will allocate a physical page and create a page table entry for it. This means that, when the next module is loaded, it has access to the services of the already loaded modules. The shell executes the specified interpreter on operating systems that do …

You can do almost anything with it, including software installation, application and server configurations, file system management and much more. Think about other software you use everyday that is proprietary and apply the fact that you can't be sure what it is actually doing! Networking the critical aspects of a …

There are no set boundaries or any limitations. The visibility and easy access to the source code, which I mentioned earlier, can also be a double-edged sword as bad-intentioned people can find vulnerabilities and leave backdoors for future exploits. Processes begin life as executable object code, which is machine-runnable code …

Every process except the first has a parent. So, if the operation value is 2, then -2 is added to the adjustment entry for this semaphore. It is as old as computers themselves. What does this mean to you?

At the Linux terminal with Firejail

Each device driver tells the operating system how to use that specific device. The process tree is rooted at the first process, known as the init process, which is typically the init program. By and throughout the 1990s, you could find MINIX installations thriving in universities worldwide-and a young Linus …

In commercial UNIX development houses, the entire system is developed with a rigorous policy of quality assurance, source and revision control systems, documentation, and bug reporting and resolution. This was the beginning of techniques such as license keys. This is true even if the device is a modem being used …

From the filename, the kernel obtains the inode number. The command cd may be run without a location as we saw in the shortcut above but usually will be run with a single command line argument which is the location we would like to change into. A block device cannot …

But Unix has a much richer history beyond those bearded C programmers from the 1970s. By the time I was done, I had actually forgotten how to use my old piece of proprietary garbageware. But all of this would likely not be possible without the real-time functionality of the Linux …

Whereas pwd is just run by itself with no arguments, ls is a little more powerful. If this execution fails because the file is not in executable format, and the file is not a directory, it is assumed to be a shell script, a file containing shell commands. They are …

In this way, the Internet acts as the glue that binds together Linux developers in particular and OSS developers in general. Built in to the structure of the command-line environment are dozens of commands and several text-based help systems. Now, imagine that the execution of all the above commands is …

To make sure that even in a dual boot scenario office staff do not cling to their past desktop but acclimate quickly to the new desktop simply requires a "conversion plan." All of the employees know they will have a dual boot system that is fully functional for the first …

Interestingly, the ability of bash scripting is also one of the most compelling reasons why programmers prefer using Linux OS. Linux has two types of system timers, both queue routines to be called at some system time but they are slightly different in their implementations. Most open source Internet tools …

Of course, most system calls have only a couple of parameters. So now you are probably starting to see that we can refer to a location in a variety of different ways. The saved uid stores the original effective uid; its value is used in deciding what effective uid values …

Because Linux has such a large number of contributors from across multiple decades of development, contacting each individual author and getting them to agree to a new license is virtually impossible, so that Linux remaining licensed under the GPLv2 in perpetuity is all but assured. Linux tracks the usage of …

The issues with the Diebold [2] voting systems in the US is testament [3] to the need for transparent systems that are trustworthy. In the above example, the vfat and msdos modules are both dependent on the fat module and so it has a count of 2. For Linux, a …

For those companies, Linux supports most UNIX commands and standards, which makes transitioning to Linux very easy because the company likely would not need to pur- chase additional software or retrain staff. Also, the kernel compilation process is not as verbose in the 2.6 kernel series. A question that …

Where does the bash fit in? The keyboard, mouse and serial ports are controlled by a SuperIO chip, the IDE disks by an IDE controller, SCSI disks by a SCSI controller and so on. Linux is believed to comply with POSIX.1 and SUSv3, but as no official POSIX or …

In addition to the real uid, each process also has an effective uid, a saved uid, and a filesystem uid. The terminal in Linux is a wild card. Whereas sockets communicating over the Internet might use a hostname and port pair for identifying the target of communication, Unix domain sockets …