The IP protocol layer itself uses many different physical media to transport IP packets to other IP hosts. If you look at the output of lsmod, you will see that each module has a count associated with it. Until recently, most modems were 8 or 16 bit ISA cards. While …

The instructions executed by the processor are very simple; for example ``read the contents of memory at location X into register Y'. The target host that owns the IP address, responds with an ARP reply that contains its physical hardware address. Staff and students in the school have the tcsh …

Every device in the system is represented by a device special file, for example the first IDE disk in the system is represented by /dev/hda. But there may have a possibility of spreading malware to the Linux based systems if they are connected with Windows based systems. This is …

There are also numerous completely free resources available on the Internet, including (1) tutorials, (2) books and (3) newsgroups. This might seem a very unreliable method but every process in the system is making system calls, for example to write a character to the terminal, all of the time. In …

So when you're writing something in your word processor and you want to check out something on the web, no need to review all your windows to find your browser, stacked all the way behind the others. Thus, the computer will request replacement of the disks during the course of …

By calling bash executable binary explicitly, the content of our file date.sh is loaded and interpreted as Bash Shell Script. For most users, LILO works best. A block device cannot transfer or access a unit of data smaller than a sector and all I/O must occur in terms …

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. They prefer the term open …

If you find a bug, report it! The format most common in Linux is called Executable and Linkable Format (ELF). But all things come to an end eventually. You would want that file access to be strictly coordinated.

How much do you know about the Linux rlogin command?

A non-zero exit status indicates failure. Linux, on the other hand, builds on the Unix tradition by offering tried-and-true tools. The first IDE controller in the system is known as the primary IDE controller, the next the secondary controller and so on. This means that you cannot DMA directly into …

Everyone has a favorite development platform. These registered port addresses can be seen in /etc/services. Another important feature of Linux is that it can run on a variety of different computer hardware platforms frequently found in different companies. The POSIX standard was born in 1988, as well as other …

The vm_next_shared and vm_prev_shared pointers are used to link them together. A real-world example of an API is the interfaces defined by the C standard and implemented by the standard C library. In other words, a thread is the abstraction responsible for executing code and maintaining the process's running state …

Libraries were written and ported, filesystems developed, and hardware drivers written for many popular devices. An exit status of zero indicates success. Tied closely to IoT is the drone trend, that of remotely controlled flying robots. A character device is accessed as a linear queue of bytes.

Shortcuts for nameif …

(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 second, newer, mechanism uses a linked list of timer_list data structures held in ascending expiry time order. In most cases, good results can be obtained by just using the default options. Every distribution contains hundreds or thousands of programs that can be distributed along with it, and each of …

The most interesting case recently was when Sony purposely added spyware [4] to their music CDs that silently and automatically installed itself onto Microsoft Windows systems to search for piracy breaches. Only the truly dedicated -- those who have no personal lives, or those who are being paid to do this …

The GPL subsequently became by far the most widely used license for free software. Currently, in Distrowatch's past 6 months ranking, it sits at #3. Linux is a topic which is equally suitable for study in the classroom (such as at a university or a specialized computer school) or at …

Yes, the house is ruining the sacred area, but nobody informed the homeowner in question about this problem before the purchase, so the shame should be placed elsewhere. This is also in sharp contrast to Microsoft Windows, for which modification of the software is generally not permitted. Mounting other filesystems …

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 …

The world economy will not collapse if creators of software choose to share their work with the world. When adding a user to a system you will be asked for your root i.d. In all of the cases above, the synergy created between the pairs has only gone to …

Now synonymous with private cloud computing, the OpenStack cloud framework likely would not exist, or at least would be incredibly different, without Linux. According to the Stack Overflow 2016 survey, desktop developers now constitute just 6.9 percent of all developers (and that also includes Mac Desktops). Without Linux as …

It is as old as computers themselves. As the information age went on, though, corporations became progressively more obsessed with controlling the spread of knowledge. The boom in interest around the Internet of Things (IoT), the notion of a network of devices, big and small, that can "talk" to each …

This modest computer's official Raspbian OS comes loaded with tons of programming tools, connector pins, and other useful ports. We are not done with hardware vulnerabilities, and speculative-execution vulnerabilities in particular. Alternatively, the process may have specfied its own signal handler. But imagine that if you can delete this system …

By contrast, most software carries fine print that denies users these basic rights, leaving them susceptible to the whims of its owners and vulnerable to surveillance. There is no problem with using an older computer, for example, an elderly 500MHz Pentium PC with as few as five gigabytes of hard …

A server is a computer with an operating system that is configured to allow other computers to connect to it from across a network. This is one of those arguments that sounds good superficially but which is not borne out by the evidence. If you plan to incorporate such software …

As the writing process writes to the pipe, bytes are copied into the shared data page and when the reading process reads from the pipe, bytes are copied from the shared data page. To make it easy to find, the current, running, process is pointed to by the current pointer …

In the Linux world, a large number of users will always prefer to compile applications from source, rather than using an installer package. Outsource open source software development to O2I and benefit from high-quality services at a cost-effective price. However, that can leave your Linux system vulnerable to attack, and …

The Linux kernel, supporting both preemptive multitasking and virtual memory, provides every process both a virtualized processor and a virtualized view of memory. This is true even if the device is a modem being used by the PPP daemon to connect a Linux system onto a network. Therefore Linux adds …

Therefore, when moving to the PDP-11 as the main hardware platform, the developers started C as the as a core language for Unix. Advocates of copyleft respond by pointing out that there is no such thing as absolute freedom. The test and set operation is, so far as each process …

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 …

Its purpose is to provide a financial incentive for producing such works in order to benefit society as a whole. It also has a utility to let you select real-time kernels. The systemd-boot bootloader generates a menu of boot image options, and can load any EFI boot image. When a …

All of the read/write heads are attached together, they all move across the surfaces of the platters together. Some users have reported success configuring and installing drivers for the various winmodems, including Lucent, Conexant, and Rockwell chipsets. Yet throughout many school systems, the software in use on computers is …

Authorization in Linux is provided by users and groups. This is also true for a number of major system tasks where the hardware and software must cooperate closely to achieve their aims. It was unbelievably naive of them to think they could stop the spread of an idea. Later on …

Initially, there is only one directory on the disk, the root directory. But note that this book does not cover the Linux programming environment -for example, there is no tutorial on make in these pages. The count is the number of kernel entities that are dependent on this module. In …

However, this is no less "programming" than anything else. On these foundationless grounds, what would be the problem with using Skype and locking not only yourself, but also all of your friends, into one company's software and protocol? It uses YUM for package management. A host wishing to know the …

Linux is a popular platform for everything from middleware to embedded computing and clusters, to parallel supercomputers and gadgets. Anyone who knows what they are doing is welcome to develop for the core, and submit patches. All controllers are different, but they usually have registers which control them. A block …

It will recognize a multiline header if the last character on each line but the last is a left parenthesis or comma. In general, failing to agree with the standards is considered a bug. So, be prepared. The key to success with studying at home is strong motivation.

Has col …

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 …

Perhaps the most confusing thing about installing Linux for new users is the large number of options that are available to choose from. The early popularity of distributions like Slackware and then Red Hat gave the "common PC user" of the 1990s access to the Linux operating system and, with …

In this case, Direct Memory Access (DMA) controllers are used to allow hardware peripherals to directly access system memory but this access is under strict control and supervision of the CPU. This creates a new vm_area_struct data structure describing the shared memory for this process. The thrust behind Linux development …

Finally there is the main memory which relative to the external cache memory is very slow. Yes, it behaved slightly differently, but I found I could be much more efficient - while using Free Software! There are various other techniques how to define shell interpreter, but this is a solid start …