As such it is possible to have two or more files and directories with the same name but letters of different case. I say somewhat, because the use of sed in conjunction with pipes is somewhat more comfortable (at least to this author) for substitution of text in files. Software …

Hard links allow for complex filesystem structures with multiple pathnames pointing to the same data. You may need to go through several rounds of resubmission and additional feedback before your code is accepted, and in some cases it may be rejected. Share your personal experiences (good and bad) with Linux …

The smallest addressable unit on a block device is the sector. With the connection established both ends are free to send and receive data. When it is started up, usually at system boot time, it opens up an Inter-Process Communication (IPC) channel to the kernel. At kernel initialization time, the …

The default action for the SIGFPE signal will core dump the process and then cause it to exit. Any of the bytes within a file may be read from or written to. Through virtual memory and paging, the kernel allows many processes to coexist on the system, each operating in …

The read/write heads are moved across the surface of the platters by an actuator. The Linux kernel, supporting both preemptive multitasking and virtual memory, provides every process both a virtualized processor and a virtualized view of memory. Other common sections in ELF executables are the absolute section (which contains …

Unlike Windows, Linux requires each user to have an account. Linux keeps looking through the pending list from the start until there is a pass where no semaphore operations can be applied and so no more processes can be woken. Effectively, they define system programming, or at least a common …

An alternative to purchasing a Linux book is to borrow one (or many) from a library; it is likely that some of them will also contain CDROMs that can be used to install Linux. And the vast profits being amassed by some of those corporations added to the frustration. Instead …

Processes are free to use a FIFO so long as they have appropriate access rights to it. You can customize the terminal, try different text editors, and install desktop environment of your choice. These accounts are combined in to groups to help simplify their management. Every process runs as a …

The new vm_area_struct structure is put into the list of vm_area_struct pointed at by the shmid_ds. Some such devices are partionable, which means that they can be divided up into multiple filesystems, all of which can be manipulated individually. Sustainable technologies are also important, and the best example of the …

However, such programs are typically also made available for free (usually as a free download from the Internet). For example, on your computer, as a normal user you may have permission to access other files on the system. This waiting happens within the system call, in system mode; the process …

The module data structure is marked as DELETED and it is unlinked from the list of kernel modules. Most licenses of the proprietary software systems are expensive and should be renewed every year. These range from simple memory protection schemes to complex page hierarchies. You don't need to spend tons …

Therefore Linux adds a call to a tidy up routine which will restore the original blocked mask onto the call stack of the signalled process. If your computer came with a copy of Windows, then you paid for it, even if the store didn't tell you about that. This credit-card …

If the name doesn't give it away, Linux containers, a method of packaging and isolating an application with only its dependencies, are a technology built from key pieces of the Linux kernel. Still, this survey does compare Windows 2000, GNU/Linux (up to 497 days usually), FreeBSD, and several other …

First of all the DMA controller knows nothing of virtual memory, it only has access to the physical memory in the system. If they will then it removes the sem_queue data structure from the operations pending list and applies the semaphore operations to the semaphore array. Institutions that rely solely …

If you're interested in writing code for the Linux kernel itself, a good place to get started is in the Kernel Newbies FAQ, which will explain some of the concepts and processes you'll want to be familiar with. This chapter describes how the Linux kernel manages the physical devices in …

You can customize the terminal, try different text editors, and install desktop environment of your choice. The results of such concurrent accesses rely on the ordering of the individual operations, and are generally unpredictable. Writing a byte to the middle of a file overwrites the byte previously located at that …

If you find a bug, report it! On i386, for example, a user-space application executes a software interrupt instruction, int, with a value of 0x80. However, such programs are typically also made available for free (usually as a free download from the Internet). Maybe it's a Linux firewall on a …

Even so, most software developers, even those who have grown up during this venerable "Linux revolution" have at least heard of Unix. While early drones relied on proprietary operating systems, the boom in drone flight is helped onward by Linux, which provides the tiny embedded operating systems necessary to run …

Like interrupts, some devices have a fixed DMA channel. Most processes consist of only a single thread; they are called single-threaded. The data is read by a head, which can detect whether a particular minute particle is magnetized. On GNU/Linux systems a file command can be used to identify …

Python has always touted itself as a "batteries included" language; its standard library contains lots of useful modules, often more than enough to solve many types of problems quickly. To understand what OSS is, you must first understand how source code is used to create programs. In all cases, bash …

Its latest releases often inspire the other Linux distributions to adopt new features and make changes. Just as IP packets have their own header, TCP has its own header. This integration would result in efficient administration. However, there is a fundamental difference: free software retains its copyright and is released …

Students should, at least, be given the opportunity to see how their new tools work. If a blocked signal is generated, it remains pending until it is unblocked. It's basically community version of Red Hat without any fee or support. The BSD socket layer passes the socket data structure representing …

There are various other shell interpreters available, such as Korn shell, C shell and more. The first method is most often the easiest, as long as your system UEFI boot manager allows you to disable the secure boot feature. For the operating system to accomplish this, it must contain the …

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. Critics of free software often voice fears that the freedoms and low cost of free software will lead …

In the Linux world, a large number of users will always prefer to compile applications from source, rather than using an installer package. While there are other options, the most common scripting language is Bash. It's a must try Linux distribution for those are willing to test the working of …

Linux is full of shortcuts to help make your life easier. Those programs or issues that have not yet been addressed or resolved for Linux can still reside on the original drive and remain operational as long as they are needed. Free software, as the term is usually used, and …

There are three types of partition supported by fdisk, primary, extended and logical. The examples continue, but all hit the same chord: there is no use in preventing the spread of information. The source code for proprietary software is usually not made publicly available, or, if it is, there are …

Sed is the Spanish word for thirst, Though you may thirst (or hunger, or whatever) for an easier way to do things, its name did not derive from there. As of April 2008, Linux had fewer than 100 known viruses, whereas Windows had more than 1,000,000 known viruses …

The LSB is a joint project of several Linux vendors under the auspices of the Linux Foundation (formerly the Free Standards Group). A filesystem is a collection of files and directories in a formal and valid hierarchy. Commercial programming packages, like commercial operating systems, can cost a great deal of …

We have icons too, you know. An API defines the interfaces by which one piece of software communicates with another at the source level. These processes range from things like the X Window System to system programs (daemons) that are started when the computer boots. A runnable process is one …

The fact that open source code offers complete transparency acts as an important guarantee of open standards. Constraining students to move the mouse within the confines of the instruction set of a few closed, proprietary programs merely cages those students and constrains our future. Unlike character devices, there are classes …

The IP protocol is a transport layer that is used by other protocols to carry their data. One interesting feature it has is that every instruction is conditional. This collaboration among several developers with a common need speeds up software creation, and when bugs in the software are found by …

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 first, the old timer mechanism, has a static array of 32 pointers to timer_struct data structures and a mask of active timers, timer_active. Processes can choose to ignore most of the signals that are generated, with two notable exceptions: neither the SIGSTOP signal which causes a process to halt …

It links the sock data structure to the BSD socket data structure using the data pointer in the BSD socket. The GNU C library provides more than its name suggests. The advocate could further explain why one particular distro was chosen and what software came pre-packaged/easily installed that made …

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 …

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 …

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?

You can pick up a book on Unix from the '80s and much of it will still be applicable to a modern Linux distribution today. Linux provides any tools you need as a developer to operate a scalable, secure servers. When TCP transmits its packet using IP, the data contained …

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.

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