How logname can help power your webapp

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 …

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Interesting apps based on make

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 …

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Actionable tips for mastering babeltrace

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 …

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Does mklost+found sometimes make you feel stupid?

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 …

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Acceptable parameters when the widget resource matters

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 …

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Configuration management under BioKnoppix

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 …

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Really small Python script

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 …

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Adventures with column and Arch

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 …

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Getting your Office suite up and running on Linux

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 …

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Who wants to know the mystery behind import

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 …

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Linux is Case Sensitive

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 …

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Let your Slackware terminal speak its mind

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 …

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Installing valgrind

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 …

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The secrets behind cpio

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 …

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The key to success with kbd_mode

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 …

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Getting acquainted with Joli OS

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 …

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Here's what no-one tells you about objcopy

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 …

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Fundamentals of libpipeline

It is time for the opening of the tools that will be needed to build this new age. The physical on-disk form of this mapping-for example, a simple table or a hash-is implemented and managed by the kernel code that supports a given filesystem. The reality is that not only …

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Understanding the backup generator game

Named pipes (often called FIFOs, short for "first in, first out") are an interprocess communication (IPC) mechanism that provides a communication channel over a file descriptor, accessed via a special file. I say somewhat, because the use of sed in conjunction with pipes is somewhat more comfortable (at least to …

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Succeed with atrm on Linux

Whereas pwd is just run by itself with no arguments, ls is a little more powerful. If this execution fails because the file is not in executable format, and the file is not a directory, it is assumed to be a shell script, a file containing shell commands. They are …

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How to set up the Perl environment on Ubuntu

A keyboard is an example of a character device. Not only you earn more capabilities as a developer, you also learn (sometimes the hard way) how to solve issues, monitor your machine for potential problems, configure different components and more. However, free software itself is not. The takeover of software …

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Redirecting output with Feather

Internal commands are, as you might expect, built into the shell program. In contrast, the source code for closed source operating systems is not released to the public for scrutiny, which means customers must rely on the vendor of that closed source operating system to provide secu- rity. Frequent emails …

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Never mess with e2fsck and here's the reason why

The job of cache coherency is done partially by the hardware and partially by the operating system. One side note is that the popularity of the macOS hardware and operating system as a platform for development that mainly targets Linux may be attributed to the BSD-like macOS operating system. There …

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What's the purpose of the CHECKSUMS.md5.asc file?

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 …

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Listen to the radio at the DamnSmallLinux command line

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 …

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A simple guide to cardctl

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

Each process consists of one or more threads of execution (usually …

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as tsort gone past its sell by date?

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 …

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Sick and tired of using showmount the same way?

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 …

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Here's what no-one tells you about timeout

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 …

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