Studying in a classroom environment can be the best choice for people who (1) prefer classes to self study, (2) do not have their own computer, (3) are lacking in motivation or study skills or (4) receive some type of tuition assistance or other grants to cover the costs of …

This means that when the next process that attempts to access this memory gets a page fault, the shared memory fault handling code will use this newly created physical page for that process too. Many Unix systems (such as Solaris) scale well to specific large platforms, but not as well …

An exit status of zero indicates success. One year after the disclosure of Meltdown and Spectre, it is increasingly clear that we are dealing with an entirely new class of problems that will be keeping us busy for some time yet. A CPU is a small but powerful semiconductor device …

The platters are attached to a central spindle and spin at a constant speed that can vary between 3000 and 10,000 RPM depending on the model. These applications are not going away anytime soon. When there are no more characters left to read, the device returns end-of-file (EOF). The …

The name is an acronym for the 'Bourne-Again SHell'. Track 0 is the outermost track and the highest numbered track is the track closest to the central spindle. If no output_file is supplied, output goes to stdout. The maximum file length, as with the maximum file position, is bounded only …

True, they are often needed for one project or another and can be well worth the cost, but for a beginner or a learner -- and for many professionals -- free software is simply irreplaceable. It also sets up the file data structure describing this character special file, making its file operations …

If a developer needs a VM or if IT Ops needs to provision a server, they expect to do so quickly and painlessly; Linux's scalability allows for this rapid provisioning, as does its lack of cost-prohibitive licensing. The Linux command line offers a wealth of power and opportunity. A good …

The API user (generally, the higher-level software) has zero input into the API and its implementation. The file position starts at zero; it cannot be negative. Processes are generally associated with a user's login group, not any of the supplemental groups. (Even of the large corporately-funded developer base, many have …

The major identifier for the primary IDE controller is 3 and is 22 for the secondary IDE controller. The GPL subsequently became by far the most widely used license for free software. The analogy is also frequently made with recipes for cooking food. Multiple processes are free to read from …

There are many ways to make money, so why choose a method that requires investing just as much time and effort into making software that lots of people want to use as trying to prevent the usage of said software? Most shells offer a similar set of internal commands, but …

Mostly Linux kernel modules are device drivers, pseudo-device drivers such as network drivers, or file-systems. The IP protocol layer itself uses many different physical media to transport IP packets to other IP hosts. Software and other creative works enter the public domain only if the author deliberately surrenders the copyright …

From there, the kernel gets the inode for plunder. You probably only have one screen, right? The routine will be called when the element on the task queue is processed and it will be passed a pointer to the data. Even when you're programming in another language, the C library …

The basics of Unix programming have existed untouched for decades. So, if the operation value is 2, then -2 is added to the adjustment entry for this semaphore. Linux provides kernel memory allocation and deallocation routines and it is these that the device drivers use. Relative to the on-CPU cache …

This hides the underlying differences from the generic system calls which read and write to ordinary files. It was a failure. When it boots, it automati- cally looks for a GRUB 2 bootloader image file named grubx64.efi, also in the uefi folder on the system. Windows 10 is perhaps …

Although directories are treated like normal files, the kernel does not allow them to be opened and manipulated like regular files. Any ethernet frame transmitted to that address will be received by the addressed host but ignored by all the other hosts connected to the network. Some operating systems, such …

It will even automatically look for requests for missing or non-existent web pages, known as 404s. Most of the servers that hold the entire internet are Linux-based for many reasons that will not be listed here. The access file logs every visit to your web site. The shell program is …

Another great quality of this dependable Linux distro for developers is its software delivery method. 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. Advocating Linux is rarely an easy task. The saved …

Absolute paths specify a location (file or directory) in relation to the root directory. A 100Mhz processor will receive 100,000,000 clock ticks every second. Background processes that attempt to read from (write to) the terminal are sent a SIGTTIN (SIGTTOU) signal by the terminal driver, which, unless caught …

After submitting a contribution using the process described in the documentation, you will need to be available to respond to feedback. The entire Linux kernel was written from scratch, without employing any code from proprietary sources. Instead, the kernel keeps parts of the process resident in memory to allow the …

The history of Unix begins at AT&T Bell Labs in the late 1960s with a small team of programmers looking to write a multi-tasking, multi-user operating system for the PDP-7. GNU/Linux increases personal computing freedom. Synchronous jobs started by bash have signals set to the values inherited by …

For example, the term open source is of much more recent origin. Device drivers have to be careful when using memory. Those licenses must adhere to the open source definition but might contain extra conditions that the open source defini- tion does not. It is interruptible, so it can receive …

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 …

If the command name contains no slashes, the shell attempts to locate it. The most precious resource in the system is the CPU, usually there is only one. The proto_ops data structure consists of the address family type and a set of pointers to socket operation routines specific to a …

Aliases are expanded when a command is read, not when it is executed. Commands run as a result of command substitu- tion ignore the keyboard-generated job control signals SIGTTIN, SIGTTOU, and SIGTSTP. People who are completely new to open source software often wonder how a group of random people can …

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 …

That is, there are no legal restrictions on anyone using, studying, copying, modifying, improving or publishing any recipe. Luckily, basic maintenance and basic security are pretty easy. One of the best parts about Gentoo, which is also a curse for some people, is its ability to configure what compilation flags …

The API merely defines the interface; the piece of software that actually provides the API is known as the implementation of the API. Finally, when the connection is no longer needed it can be shutdown. Once connection has been made, any of the (usually) several browsers available can be used …

However, this is definitely no loss. Big data, the collective term for the mountains of information produced by businesses, can hold the keys to more efficient operations and even increased revenues by identifying new opportunities, but first this data must be sorted, parsed and analyzed. As you can see, the …

This, in turn, allows for the use of the pathnames with which all Unix users are familiar-for example, /home/blackbeard/concorde.png. Figure 5.1 shows that each file data structure contains pointers to different file operation routine vectors; one for writing to the pipe, the other for reading from …

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 …

Othertimes, simply booting the machine can be a chore. The entire Linux kernel was written from scratch, without employing any code from proprietary sources. A process that has terminated, but has not yet been waited upon, is called a zombie. Linux allows you to include device drivers at kernel build …

For example to display a manual page for the ls command execute man ls. Linux must handle readers opening the FIFO before writers open it as well as readers reading before any writers have written to it. You may then continue typing and hit Tab again and it will again …

Microsoft was recently discovered to be using code stolen from a competitor on a social networking site, even though the code was never released. The Systemd-boot bootloader program is starting to gain popularity in Linux distribu- tions that use the systemd init method (see the next section). A process is …

Internally, the Linux kernel implements a unique view of threads: they are simply normal processes that happen to share some resources. The only rule is that when you develop something new out of the source code, you must share that code with everyone else. The init process routinely waits on …

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 …

Developing the core is pretty serious business, involving pretty serious computer science. But the existence and popularity of the Windows Subsystem for Linux (WSL), as well as more recently announced capabilities like the Windows port of Docker, including LCOW (Linux containers on Windows) support, are evidence of the impact that …

Behavior changes and features are added. Aliases are expanded when the function definition is read, not when the function is executed, because a function definition is itself a compound command. As long as the system appears to be free of critical or oft-manifesting bugs, it is considered ``stable' and new …

This is used by gateways, which respond to ARP requests on behalf of IP addresses that are in the remote network. Many, if not most, PCI modems available on store shelves these days are WinModems. This means that subsequent INET socket calls can easily retrieve the sock data structure. Figure …

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