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.).

Linux Training Online – Using the Linux CD Command to Change Directory – Linux System Administration

As a new user looking for Linux training, you need to learn how to use commands. And one of the most commonly used file system commands is the CD (change directory) command.

Using the Linux CD Command

The CD (change directory) command is used to change from your current directory (folder) into a different directory.

You need to change into a directory to do Linux administration tasks like:

  • create a new file or remove an existing file
  • copy or move a file to a different directory
  • edit and modify a file, such as a text configuration file for a Linux server
  • create a new directory or remove an existing directory
  • copy or move a directory to a different directory

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

Linux CD Command Example – Changing into a Directory Below the Current Directory

To change directory into a directory “below” the current one, you type in CD and a space and the name of the directory you want to change into.

For example, to change into a directory named “letters”, you run the following:

$ CD letters

To change into a different directory, just replace “letters” with a different name.

Linux Training Tips: A directory inside the current one is considered “below” the current directory, and is called a sub directory.

Linux CD Command Example – Changing Up One Directory (Level)

To change directory up one directory (level), you type in CD and a space and then two dots (periods).

For example, if you have moved into the directory named “letters” and want to go back (up) to your previous directory, you run the following:

$ CD ..

Linux Training Tips: The directory above the current one is also called the “parent”.

Beyond This “Linux Training Online” ArticleThe Linux CD command is used in many other ways to navigate around the file system.

To continue your Linux training, you also need to learn how to use the CD command to: change to the root directory, change using an absolute path, and also easily change into a directory parallel to the current directory.

You can clearly and easily see all of the concepts and commands shown above (and lots more!) by watching a Linux training video.

With this method of Linux training, you can see how to use a command step-by-step and also hear how to run the command. This is a very easy way to learn how to use Linux.

Various Linux Hosting Distribution

The Linux hosting system was first introduced in 1991 and it was a well received operating system until today. Nowadays, users see Linux hosting as a wonderful replacement for Windows or Mac OS X system. Initially, it was only used as a server solution but it is making its way into homes now. One of the biggest reason for it to be so popular is because it is an open-sourced solution. This way, many developers are constantly providing new stuff for it. There are a few ways on how Linux is distributed and this is what we will take a look at in this article.

The first distribution is called Ubuntu. It is considered as the most widely used distribution channel because it is made more for a desktop compatibility instead of a server. Many of its features can match up with the Windows system. Therefore, Ubuntu is a strong player when it comes to making a choice for a hosting solution.

Next, we have the Kubuntu distribution. From its name alone, you can tell that it might have a similarity to the Ubuntu system. In fact, it is very similar to Ubuntu except that it is using a different file system. Both distribution have similar functions and are very user-friendly compared to other distribution of Linux. Therefore, many users opt for this system because they do not have to deal with complicated server management tasks.

Then, we have the Debian distribution. This distribution is a more complex system which may be a little harder for users who do not have the knowledge. This is due to its superior flexibility and performance which can be well used for either a desktop or a server environment.

Following that, we have the Fedora system. Unlike the other, this distribution is considered as a light weight distribution which often is included in dedicated hosting servers. Based on the RedHat Linux, Fedora is commonly used commercially. Therefore, it is competing with Microsoft Windows. Operating Fedora does not require big resources. It can run with limited resources but its performance will still be top notch.

Last but not least, there is the CentOS distribution. CentOS which stand for Community Enterprise Operating System are also a distribution based on the RedHat Linux but it is a free source distribution. CentOs is used for commercial development because of its stability and security.