The first data written into the pipe is the first data read from the pipe. Like the rest of the kernel, device drivers use data structures to keep track of the device that it is controlling. These controllers are connected to the CPU and to each other by a variety …

The access file logs every visit to your web site. For example, a processor could execute an instruction every clock pulse. A way to prevent that is regular updates and only download software, themes and plugns form reliable sources. It looks at each member of the operations pending queue (sem_pending …

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. Linux tracks the usage of …

In this case, Direct Memory Access (DMA) controllers are used to allow hardware peripherals to directly access system memory but this access is under strict control and supervision of the CPU. This creates a new vm_area_struct data structure describing the shared memory for this process. The thrust behind Linux development …

Modules that have other modules dependent on them must maintain a list of references at the end of their symbol table and pointed at by their module data structure. For example, software that can be freely modified but that does not have the same strict requirements for redistribution as the …

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. Built in to …

Finally there is the main memory which relative to the external cache memory is very slow. Yes, it behaved slightly differently, but I found I could be much more efficient - while using Free Software! There are various other techniques how to define shell interpreter, but this is a solid start …

Because of the diversity of the Linux community and the many needs which the software is attempting to meet, not eveything can be taken care of for you all of the time. Quite the contrary, the artisans and artists who craft software which can be shared, improved, and shared again …

The issues with the Diebold [2] voting systems in the US is testament [3] to the need for transparent systems that are trustworthy. In the above example, the vfat and msdos modules are both dependent on the fat module and so it has a count of 2. For Linux, a …

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 …

The IP protocol is a transport layer that is used by other protocols to carry their data. As the cliche goes, "If we both have an apple, and we exchange apples, we each still have one apple. It provides the interfaces documented in SUSv4 and POSIX 2008, including real-time (POSIX …

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 …

If you do this, or try to exit again immediately, you are not warned again, and the stopped jobs are terminated. Once a Linux module has been loaded it is as much a part of the kernel as any normal kernel code. This value is called the inode number, often …

As you can see, long hand command line options begin with two dashes ( -- ) and short hand options begin with a single dash ( - ). Use man command to display manual page of any desired command. There are several good reasons for becoming familiar with Linux. Where do you think Microsoft gets its …

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 …

Therefore, an alias definition appearing on the same line as another command does not take effect until the next line of input is read. Let's face it; Windows OS is vulnerable to different types of attacks (or hacks). Grep will take the output for that command, which is the name …

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 …

Proficiency with the proprietary Unixes has always been considered valuable, and it is well rewarded in the job market. The results of such concurrent accesses rely on the ordering of the individual operations, and are generally unpredictable. But I don't see the need for a true Linux Advocate to spotlight …

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 …

Linux systems always have a root filesystem. Linux does not. Signals have no inherent relative priorities. Even in the days before the Internet, information and so-called "intellectual property" could still be, and were, exchanged.

A simple guide to resize2fs

For kernel code, once it is complete the developer may ask Linus to include it in the standard kernel, or as an optional add-on feature to the kernel. An inode stores metadata associated with a file, such as its modification timestamp, owner, type, length, and the location of the file's …

For example, software that can be freely modified but that does not have the same strict requirements for redistribution as the GPL is also considered open source. This means that it's not enough for a Linux platform to support what an enterprise needs right now. People who are completely new …

Although initially intimidating for many inexperienced users, using an all-text mode, also referred to as a command line interface (CLI) or a shell, can provide valuable experience for those who want to become truly proficient at Linux. Even so, most software developers, even those who have grown up during this …

Linux is open-source. With all the activity around Unix at Berkeley, a new delivery of Unix software was born: the Berkeley Software Distribution, or BSD. Furthermore, the developer writing Python or Ruby or Scala can still benefit from knowledge of system programming, as an understanding of the soul of the …

It is vital that there is an uninterrupted stream of knowledge, and that information is not held back for personal benefit at the cost of others. Most of the time you will be issuing commands. Anyone can join the Linux community by participating in and contributing to this mailing list …

Public domain refers to the total absence of copyright protection. Normally, Linux would suspend the requestor, putting the process onto a wait queue until there is enough physical memory. It sounds counterintuitive and/or just plain stupid on paper, but is generally seen as the traditional and conservative way to …

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 …

Now Linux must check that any waiting, suspended, processes may now apply their semaphore operations. Much of enterprise IT's excitement is focused on advancements at the application level (and rightly so), but it's Linux that powers these innovations and helps to drive modern computing forward. If you're interested in writing …

Linux (as well as many other areas of information technology) is particularly well suited for studying at home because (1) no equipment is needed other than an ordinary personal computer and (2) there is a large amount of free or modestly priced study material that is available from bookstores, in …

The device identifier for the first partition of that disk (/dev/hdb1) is (3,65). Shell scripting is really what separates novice Linux consumers from advanced Linux users. This is why our previous shell script works even without us defining bash as an interpreter. The inode contains metadata associated with …

In addition to the real uid, each process also has an effective uid, a saved uid, and a filesystem uid. The terminal in Linux is a wild card. Whereas sockets communicating over the Internet might use a hostname and port pair for identifying the target of communication, Unix domain sockets …