Brief Introduction to the Plan-9 Operating System

Plan 9 is a distributed operating system made by Bell Labs. The OS is free and open source. Plan 9 is similar to Unix in some ways, but Plan 9 is meant to be an improvement to Unix and POSIX.

FUN FACT: The mascot for Plan 9 is a rabbit named “Glenda”.

Plan 9 has some features familiar to Unix users. For instance, Plan 9 uses ProcFS and applies the “everything is a file” concept. However, applications from Unix, Linux, and other systems do not work on Plan 9. Some Linux software works on the Linux emulator (linuxemu). Although, the emulator is not yet complete.

The default shell is “rc”. Many of the usual Unix commands (like ls, cp, rm, etc.) can be used. However, despite the same names, the code used to make these commands are entirely different. Plan 9 does not use any GNU software, neither will any work with help from linuxemu. rc is similar to Bash. However, there are some differences. While Bash’s syntax is ALGOL-like, rc uses C-like syntax.

A GUI is also available to Plan 9 named “rio”. rio is a windowing system. rio does not rely on display servers (such as X11). In fact, rio functions as a display server and window manager. rio supports the alpha bit (transparency).

Plan 9 uses a hybrid kernel which has attributes of both monolithic kernels and microkernels. The kernel supports a variety of platforms such as x86, x86-64, MIPS, SPARC, etc.. Plan 9 has also been ported to ARM platforms such as the Raspberry Pi motherboard.

A hybrid kernel has characteristics of both microkernels and monolithic kernels. Inter-Process Communication (IPC), thread management, filesystems, and drivers reside in the kernel space.

Plan 9 is best known for its 9P network protocol. 9P (also called Styx or “Plan 9 Filesystem Protocol”) also serves as a communications protocol between the internal components of the system. The fourth edition of Plan 9 introduced a modified 9P protocol called 9P2000.

FUN FACT: The Styx protocol used in the Inferno operating system is a variant of 9P.

To avoid confusion, it may help to know a little about the Inferno operating system, which is sometimes mistaken as some form of Plan 9. Inferno is a distributed operating system originally made by Bell Labs (like Plan 9), but is now maintained by Vita Nuova. Inferno is neither Unix or POSIX and its primary use is to be a programming environment for the Limbo programming language. Inferno is not a typical operating system. Rather, its kernel is a virtual machine called “dis” that runs on a pre-existing OS (such as Linux, Windows, Plan 9, FreeBSD, etc.).

Pediatric Dental Anxiety

Many adults today maintain anxiety about going to the dentist and attribute this anxiety to past uncomfortable or painful dental visits that they had when they were younger. They now face the prospect of their own children going to the dentist for the first time. Children going to the dentist for the first time should not have a specific anxiety about this, but we should remember that many young children have stranger anxiety, particularly towards those who enter their personal space. It is important that parents help their children overcome any developing anxiety regarding dental visits.

For children, not dealing with the fear of the dentist can have far-reaching consequences, more than many parents think. For example, an ordinarily well-behaved child who is afraid of the dentist may not cooperate with basic procedures such as dental exams, x-rays, and cleanings, making it difficult for the dentist to perform an adequate exam. Furthermore, if dental work such as filling a cavity has to be done, anxious and uncooperative children may have to be sedated in order to accomplish the necessary procedure. Finally, children who maintain dental anxiety may carry that fear into adulthood, leading to poor dental health later in life.

Parents should not expect that their child’s fears will disappear over night, but one thing that a parent can do to lower their child’s dental anxiety is to avoid reinforcing the anxiety. Even if a parent is afraid of the dentist, the parent should never display that fear in front of their child, as children respond to basic cues from their parents.

Parents may also decide on using a pediatric dentist who has been specially trained in dealing with anxious children. Not only do pediatric dentists use special tools to make the process less painful, but also their offices tend to more kid-friendly. Most pediatric dentists incorporate fun things into their office to which children are more receptive, like cartoon characters, video games, etc.

It is important for children to learn as early as possible what a dentist is and why their work is so important. Children should be taught good oral hygiene in the home and parents should explain, in the simplest way possible, that good oral hygiene saves the trouble of more invasive dental procedures later on.

A child who is anxious about going to the dentist is at risk of developing poor dental health. While any parent hates to see his or her child feel this afraid, avoiding the dentist because of anxiety is never a good decision. In fact there may always be a certain level of dental anxiety for a person of any age, but with a few simple steps, parents can greatly lower the amount of uneasiness their child feels about going to the dentist.

3 Methods of Linux System Administration and Why Linux Commands Are Best – Linux Training Online

When you are a new user needing to get Linux training, it is often confusing to decide what to focus on.

Should you learn how to use Linux for just one distribution (a.k.a. version, distro)?

Should you focus on learning GUI utilities – or should you learn Linux commands for doing system administration?

Linux Commands Training Tips: The Linux System Administration concepts and commands covered here apply to ALL Linux distros, including: Red Hat, Ubuntu, Kubuntu, Edubuntu, Slackware, Debian, Fedora, SUSE and openSUSE.

3 Methods of Linux System Administration and Why Using Linux Commands is the Best Method

1. Using Linux GUI utilities for System Administration

Many Linux distributions have “point-and-click” GUI (graphical user interface) utilities that allow you to do common and popular tasks, like manage the file system, create Linux users, and manage user and group permissions.

However, these GUI utilities are usually specific to a single Linux distribution.

So, learning how to use a Linux GUI in one distro is basically useless if you have to use a different one later, or if you’re working in an environment with multiple Linux distributions.

Linux Training Tips: To run a GUI utility, you need to have a desktop installed and sometimes one isn’t installed on a Linux server because it isn’t needed. In addition to this, the Linux system administration pros only use commands because GUI utilities are too slow to run and time-consuming to use.

2. Doing Linux System Administration Tasks with Commands that are Specific to a Distribution

The major (popular) Linux distributions all have several commands that are specific to that single distribution. In other words, for each popular distro, there are several commands that are specific that just that version.

For example, a Linux distribution will likely have a command that is used to manage partitions (disk space) and this command is specific to that distribution.

Learning how to use commands that are only available on a single distribution is a huge waste of time – if there is an equivalent GNU / Linux command – and there almost always is.

For example, the Linux fdisk command is a GNU command that is used to manage the partitions on a system and this command exists on all distributions.

So, rather than learn a command that is specific to a single Linux distribution, learn the GNU commands because these commands are common to all distributions.

3. Using Linux Commands that are Common to All Distributions – The GNU Commands

The GNU commands are the most popular Linux commands – and they are common to all distributions.

Linux Training Tips: Linux distributions are rising and falling in popularity all the time.

If you just learn how to use Linux by running the GUI utilities in one distro, and then you stop using that distro, then you have to learn all the GUI utilities of the next distro. If you learn how to use commands, then you learn how to use Linux for all distros!

How can you tell which commands are the GNU / Linux commands?

Get an excellent set of videos that shows you the popular GNU commands and then try these Linux commands yourself. Then you can learn Linux the easy way – by watching it and then working with it!