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

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 …

It also helps to know how to access the Internet and be able to do basic web searches with a search engine such as Yahoo or Google. Of course, we knew that all along. This means that subsequent INET socket calls can easily retrieve the sock data structure. For example …

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 …

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 …

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 …

The Watergate scandal leaked to the press through one of US President Nixon's most trusted colleagues. Device drivers have to be careful when using DMA. By the time I was done, I had actually forgotten how to use my old piece of proprietary garbageware. Linux is open-source.

How much do …