Like the virtual filesystem, Linux abstracts the socket interface with the BSD socket layer being concerned with the BSD socket interface to the application programs which is in turn supported by independent address family specific software. This is especially important if a particularly vital application does not yet exist for …

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 …

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 …

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 …

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 …

This integration would result in efficient administration. Filesystems usually exist physically (i.e., are stored on disk), although Linux also supports virtual filesystems that exist only in memory, and network filesystems that exist on machines across the network. Most processes consist of only a single thread; they are called single-threaded …

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 …

They will not begin with a slash. In general, failing to agree with the standards is considered a bug. Not all four entries in the partition table have to be used. None other than the system call handler!

Scan the results of parameter expansion

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 …

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 …

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 other is part of OpenOffice, a full-fledged office productivity suite that is comparable to and compatible with Microsoft Office. Oracle Corporation, another heavyweight in the DBMS industry, recently announced it would be creating a Linux compatible Oracle. Likewise, some minimal restrictions are necessary for free software, namely the GPL …

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 …

In general, there is a tendency for advocates of the term term free software to emphasize the ideological aspects of software, including the ethical or moral aspects, and they view technical excellence as both a desirable and an unavoidable by-product of their ethical standards. The shell learns immediately whenever a …

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 …

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 …

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 …

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 …

Whenever a VFS inode representing a character special file is created, its file operations are set to the default character device operations . For this reason, it is referred to as Open Source Software (OSS). Rather than having to satisfy a set of needs laid out by a single department head …

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 …

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 …

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 …

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

But it starts at the top. For Linux, a vendor can create a device driver for a specific hardware device and expect that, within reason, it will operate across most distributions. When Corporations are happy with the used software they donate money to the communities in order to be able …

Functions are defined by using the function keyword and followed by function body enclosed by curly brackets. The data is read by a head, which can detect whether a particular minute particle is magnetized. FLOSS OSes tend to include many applications that are usually sold separately in proprietary systems (including …

The UEFI boot manager boots the mini-bootloader, then, in turn, it boots the standard Linux bootloader image. The exact wording of a recipe as it is written by its author is protected under copyright law, but the information itself (i.e., the names of the ingredients, their quantities and the …

Why make it easier for them. However, in most cases it is closed source (i.e., the source code is kept secret), and there are often restrictions on the use of the executable version. If all of the semaphore operations would have succeeded and the current process does not need …

In a multiprocessing system many processes are kept in memory at the same time. The kernel does not impose any restrictions on concurrent file access. This software universe had been going on behind my back for years. Just maybe that crash you reported will save some people from a major …

Processes that are started at boot time usually run as root or nobody. As a Linux user today you have all the means of getting to know your system inside out, but it is no longer necessary to have that knowledge in order to make the system comply to your …

Figure 11.3 shows both mechanisms. For example, %ce refers to a stopped ce job. The partitions of a hard disk are described by a partition table; each entry describing where the partition starts and ends in terms of heads, sectors and cylinder numbers. If something is in the public …

All of the read/write heads are attached together, they all move across the surfaces of the platters together. A common sector size is 512 bytes and the sector size was set when the disk was formatted, usually when the disk is manufactured. There is yet one other weakness: if …

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 …

Therefore, mastering Linux for configuring and maintaining servers is a must to have skill for any technological entrepreneur who operates end-to-end applications. The scalability and flexibility of Linux enable many of these massive deployments to actually work, while the significantly reduced cost barriers of Linux make them more financially feasible …