This makes kernel memory deallocation easier as the smaller free blocks can be recombined into bigger blocks. This means that the process can continue to run. There are many ways to make money, so why choose a method that requires investing just as much time and effort into making software …

Writing a byte to the middle of a file overwrites the byte previously located at that offset. Conceptually, nothing covered thus far would prevent multiple names resolving to the same inode. Without this surrounding commitment, IT decision-makers can be left in the dark...and that's not a good place to …

When a command terminates on a fatal signal, bash uses the value of 128+signal as the exit status. Let's look at creating an image file so we can start a container which we created. Much of enterprise IT's excitement is focused on advancements at the application level (and rightly …

Some operating systems, such as VMS, provide highly structured files, supporting concepts such as records. Linux maintains the set of registered block devices as the blkdevs vector. A process is also associated with various system resources, which are arbitrated and managed by the kernel. Its own Software Center has tons …

The GNU C library provides more than its name suggests. The tools philosophy was to have small programs to accomplish a particular task instead of trying to develop large monolithic programs to do a large number of tasks. Let it suffice to say that not every single bug has been …

It's basically community version of Red Hat without any fee or support. Thus, there is no term free mathematics. Soon enough this will become an extremely tedious task destined for failure. The caricatures speak of wizard-like "graybeards" sitting behind glowing green screens, writing C code and shell scripts, powered by …

Users of closed source operating systems must report the bug to the manufacturer and wait for the manufacturer to develop, test, and release a solution to the problem, known as a hot fix. Unlike the MINIX filesystem before it, ext could address up to 2GB of storage and handle 255-character …

Richard Stallman's stallman.org is a perfect example. This behaviour has spawned a whole new wave of viruses and is a gross breach of privacy. It will recognize a multiline header if the last character on each line but the last is a left parenthesis or comma. Much of enterprise …

This allows the ethernet layer to correctly receive IP packets and to pass them onto the IP layer. The boot disks are located in the bootdisks/ directory in the distribution tree. Indeed, they even have associated inodes. It is vital that we keep a philosophical approach so that our beliefs …

Whereas MINIX is based on a microkernel that contains the bare minimum amount of code necessary to run an operating system, Linux has a monolithic kernel, which means that functions like the file system, virtual memory, and various system calls all take place in privileged kernel space. But the existence …

The first thing I do when I get a new computer is format my drive and install Linux. 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 …

The kernel allocates a new module data structure and enough kernel memory to hold the new module and puts it at the end of the kernel modules list. By virtue of its open source licensing, Linux is freely available to anyone. People who develop OSS commonly use the Internet to …

You can easily see the exported kernel symbols and their values by looking at /proc/ksyms or by using the ksyms utility. 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 …

This is one of those arguments that sounds good superficially but which is not borne out by the evidence. If the thief runs, he/she probably won't get caught, and it is a quick way to make some extra cash. If you've always wanted to learn programming, whether you want …

You can control everything from the command line. There is yet one other weakness: if a computer switches operating systems later, the long uptime is credited to the new OS. Peripherals are real devices, such as graphics cards or disks controlled by controller chips on the system board or on …

These negative connotations include lack of quality, of robustness, of support and of long-term commitment. The shell program is what presents the prompt and accepts subsequent commands. This means that it's not enough for a Linux platform to support what an enterprise needs right now. Copyright does not protect facts …

Processes are allowed to do non-blocking reads (it depends on the mode in which they opened the file or pipe) and, in this case, if there is no data to be read or if the pipe is locked, an error will be returned. When processes are deleted, as they exit …

Processes are free to use a FIFO so long as they have appropriate access rights to it. Most people believe it is wrong to steal, and therefore, won't rob a wallet. Today open source software has become critical for almost every organization. The access file logs every visit to your …

Institutions that rely solely on commercial-proprietary vendors - whether on-premises or cloud-based - effectively outsource their IT strategy and reduce their capability to deal with change with agility. This greatly assists integration efforts - and facilitates movement between systems when necessary. But, due to some recent changes, Ubuntu has switched back to GNOME …

When a user-space application requests that a given filename be opened, the kernel opens the directory containing the filename and searches for the given name. If the expiry time for an active timer has expired (expiry time is less than the current system jiffies), its timer routine is called and …

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 various steps in their processing) is not. Even so, if a process executes until it waits then …

The read/write heads are moved across the surface of the platters by an actuator. The BSD socket layer passes the socket data structure representing the BSD socket to the INET layer in each of these operations. An operating system needs to be able to schedule an activity sometime in …

federal government. A pipe (its two file data structures, its VFS inode and the shared data page) is created in one go whereas a FIFO already exists and is opened and closed by its users. Another disadvantage of Open Source is the support service. If the expiry time for an …

Compare this to a floppy disk which only spins at 360 RPM. In fact, it seemed so obvious that the situation with regard to software resembled that of mathematics or recipes that terminology such as free software, freeware and open source software did not exist for many years. The terminal …

If the process has not blocked the signal and is waiting but interruptible (in state Interruptible) then it is woken up by changing its state to Running and making sure that it is in the run queue. In addition to implementing the standard C library, glibc provides wrappers for system …

Closed source software can be distributed for free or for a cost; either way, the source code for the software is unavailable from the original developers. In Linux, no further organization or formatting is specified for a file. Until Linux came along it was either Windows or Macintosh - take it …

The same good practices and understanding of the underlying system inform and benefit all forms of programming. That way you can still change the GRUB 2 bootloader image without having to worry about the digitally signed shim.efi file. Because your server will be probably Linux-based as well, it will …

The price for a Windows license amounts to an average of one fourth of each new computer's price. Many of the devices you own probably, such as Android phones, digital storage devices, personal video recorders, cameras, wearables, and more, also run Linux. Linux systems always have a root filesystem. Again …

It does not obligate you to run it on a determined platform like some proprietary software. However, this is definitely no loss. Its interface with the BSD socket layer is through the set of Internet address family socket operations which it registers with the BSD socket layer during network initialization …

Some applications are written exclusively to higher-level abstractions. This means that you cannot DMA directly into the virtual address space of a process. Whenever you refer to a file or directory on the command line you are actually referring to a path and your path can be constructed using any …

Different distributions have chosen varying approaches to file placement, software management, and other subtleties, in such a way that makes it almost impossible to make an applications distribution that will install and run cleanly across the Linux spectrum. For people wanting to become more than just casual users, it can …

The new vm_area_struct structure is put into the list of vm_area_struct pointed at by the shmid_ds. Internally, the quality assurance department runs rigorous regression test suites on each new pass of the operating system, and reports any bugs. It then restores the state of the new process (again this is …

The U-Boot bootloader program can boot from any type of disk, and load any type of boot image. Linux can do everything NT does, usually faster, definately more stable and at a fraction of the cost. Both have similar tools for interfacing with the systems, programming tools, filesystem layouts, and …

This means that if a system has two IDE controllers there will be entries for the IDE subsystem at indices at 3 and 22 in the blk_dev and blkdevs vectors. When someone detects a bug it reports it to the community and they release a patch as soon as possible …

It was coined in 1997 with the intention of replacing the term free software in order to avoid the negative connotations that are sometimes associated with the word free and thereby make it more attractive to corporations. Hard links do not incur this additional overhead-there is no difference between accessing …

How these modes are supported by the underlying hardware differs but generally there is a secure mechanism for getting from user mode into system mode and back again. Given that Linus was using several GNU tools (e.g., the GNU Compiler Collection, or GCC), the marriage of the GNU tools …

Every transmitted ethernet frame can be seen by all connected hosts and so every ethernet device has a unique address. The pops vector is indexed by the address family identifier, for example the Internet address family identifier (AF_INET is 2). If the thief runs, he/she probably won't get caught …

Whenever a process has to wait the operating system takes the CPU away from that process and gives it to another, more deserving process. The container is when the image is running, such as loading an ISO file in Virtualbox and installing it. Writing a byte to a file position …

But it starts at the top. In many ways, Linux and UNIX administration is today much easier than administration for popular commercial personal operating systems because it is much more transparent. It stands to affect the people of the world at least as profoundly as the Industrial Age. Multiprocessing is …

There are no set boundaries or any limitations. The visibility and easy access to the source code, which I mentioned earlier, can also be a double-edged sword as bad-intentioned people can find vulnerabilities and leave backdoors for future exploits. Processes begin life as executable object code, which is machine-runnable code …