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.

Network Monitoring For Satellite Teleconference, Distance Learning, and Media Distribution

Today’s Satellite Systems

Many satellite system projects these days involve satellite uplinks with hundreds or perhaps thousands of receivers in the network receiving content from them. Traditionally, if these networks are monitored, the planners rely on SNMP traps for big troubles and plan for round-robin polling and pinging to determine the health of the receivers and other devices.

Traditional monitoring systems, because of polling speed, within an hour or two NOC (network operations center) personnel can know system status for all devices.  For example:

  • is device alive
  • can I ping it
  • is the receiver on the right channel
  • signal level
  • locked for the transmission
  • error rates

As to the traps, a little secret: many of the devices do not support traps and if they do traps can be lost because they are sent as UDP traffic with no assured delivery. Requirements for today’s professional satellite systems have evolved to the point where NOC personnel need more information and they need it more quickly. Representative are teleconference, distance learning, and media distribution systems.

For these new systems the requirements for monitoring have moved out of a strictly maintenance need to both a maintenance and operational requirement.

Teleconference and distance learning have an almost interactive need for status and data:

1. Is the receiver is on the right channel?

2. Is the feed good? Are error rates low and the signal level high?

3. If the signal is low in Milwaukee, what’s the weather like?

4. Are all of the correct materials downloaded to the receiver?

5. Are keypads and other data entry devices ready?

Media distribution systems for broadcast and digital cinema have many of the same needs and some others:

1. Is there sufficient space on the device to receive the huge files used in these operations?

2. What is the progress of the transfer (it takes a long time to transfer multi-gigabyte files)?

3. Did the digital rights management (DRM) keys arrive?

4. If it is a playout device, did the correct play list arrive?

5. Can we get the playback logs as events play?

6. What about maintenance logs, do we have to SSH into each device and retrieve them manually, or will the system automatically gather and check them for us?

These lists are representative of information the NOC needs to ensure proper operation of the network. First and second generation monitoring systems don’t even begin to broach gathering and reporting the new types of information needed to reliably operate these systems.

Third Generation Network Monitoring

Satellite network monitoring systems must have parallel collection processes in order to have sufficiently fresh data to be of value to the NOC. For many types of operations media content must be tracked. You could argue that media is not part of network monitoring and yet today’s NOC needs this information to ensure proper operation. A new generation of devices are out there delivering media content. Real time, or near real time reporting is needed to insure proper operation of these systems. New ways to visualize the network to go along with these new data sets is also required.

It’s a new game in the network monitoring world: network monitoring software has to move to the next level, including being media-aware, to meet the needs of today’s NOC for information.

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.