CBT Bazar

LinuxCBT EL-6 Edition (2011)
English | Duration: 40h | H264 | 800×600 | 5fps 137kbps | AAC 64kbps 44.1KHz | 2.74GB
Genre: eLearning

LinuxCBT EL-6 Edition focuses on the RedHat® Enterprise 6 GNU/Linux operating system.
LinuxCBT EL-6 Edition, is unparalleled in content. LinuxCBT EL-6 Edition prepares you or your organization for successfully deploying and managing business-critical RedHat® Enterprise 6-based solutions. Let LinuxCBT EL-6 Edition bolster your GNU/Linux administration skills.

Recommended Prerequisites for:
LinuxCBT EL-6 Edition
Determination to master Linux and related open-source applications
Intermediate to advanced Windows® networking skills
Understanding of networking concepts: OSI Model
Physical or virtual machine to follow exercises

More info:
_http://www.linuxcbt.com/products_linuxcbt_el-6_edition.php

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There are many ways to convert a CD to MP3 or other format, many of them as simple as point-and-click. Sometimes, though, there’s nothing quite like getting your hands dirty and using the Terminal. That’s what this article covers: ripping a CD in the Terminal using cdparanoia, and then converting those files to MP3 using LAME.

Ripping the CD with cdparanoia

The cdparanoia ripping tool is often considered among the best tools for ripping CDs available. It rips the data directly from the CD, with no analog step between, and is also good at reporting any jitter it senses while ripping, so you know that your CD rip is as close to the original as possible.

To install cdparanoia in Debian or Ubuntu, type the following into a Terminal:

sudo apt-get install cdparanoia

Any additional libraries will be pulled in and installed along with cdparanoia, and when the installation is complete, you’re ready to go.

First, let’s create a folder on the Desktop, called CDRip, where the ripped tracks will eventually land.

mkdir /home/username/Desktop/CDRip/

Now cd to the directory we just created:

cd /home/ericcflem/Desktop/CDRip/

Insert the CD, and when it has loaded, type the following command:

cdparanoia -B

This tells cdparanoia to batch rip the CDDA tracks from the CD as standard 16-bit WAV files. If you want to learn more about the nuts and bolts of cdparanoia, check out its documentation on the cdparanoia home page.

As cdparanoia works, you’ll see a progress bar for each track, as well as a smiley face which represents any errors or inconsistencies, if present.

Once the rip has ended, your folder will now be full of WAV files and it’s time to convert them to MP3.

Convert WAV to MP3 Using Perl Audio Converter

This is another simple step, which depending on your needs can be done one of two different ways. The first method uses the Perl Audio Converter, a collection of scripts which uses different command line programs to convert to and from a wide range of formats and codecs.

It does much more than we’ll use it for in this tutorial, but even if you never scratch the surface of what it can do, it’s a great tool for converting music. To install it in Ubuntu or Debian (or Mint or other derivatives), type the following:

sudo apt-get install pacpl

Just as with cdparanoia, installing Perl Audio Converter will also grab any dependencies, such as lame or other libraries. Once installed, it’s ready to use with the following command:

pacpl -t mp3 –bitrate 256 *.wav –delete

The above command invokes Perl Audio Converter (pacpl), tells it that we want to convert our files to MP3 (-t mp3), with a bitrate of 256 kb/s (–bitrate 256), then tells it to only convert wav files (*.wav), and when we’re done, to delete the originals (–delete).

While this is happening, you should see not so much a progress, as a notification that each conversion is happening, like this:

When Perl Audio Converter is done converting your WAV files to MP3, you will end up with a folder full of MP3 files, all encoded with a bitrate of 256 kb/s; the original WAV files will be deleted, leaving you nothing but the MP3 files.

Convert WAV to MP3 Using LAME

There is another method, and that is to use LAME directly to do the conversion. The big advantage is that Perl Audio Converter doesn’t offer a simple way to do variable bitrate encoding, while LAME does. The advantage to variable bitrate encoding is that each sample is analyzed and is given the correct bitrate, depending on the complexity, so you should get high quality at smaller sizes.

The command used, on the other hand, is a bit more complex:

for file in *.wav; do $(lame -V0 “$file” “${file%.wav}.mp3″); done

Basically, this says that for every file that is in WAV format, we should tell lame to encode that file using the V0 quality setting, giving it the MP3 extension, and then quit when all files have been converted. During this process, because each sample may be different, you’ll get a view of exactly what’s going on.

This shows a few things, the most important of which are the progress of the conversion, the average bitrate attained during the conversion, and and ETA for when the process will be complete.

Note: This command doesn’t delete the original WAV files, but you can do this manually or by typing “rm *.wav” (without the quotes), from the Terminal while the active folder is the one containing the music we’ve been converting.

And that’s really all you need to know about ripping your CDs and converting them to MP3. It’s a pretty quick process, and once you’re finished you’ll have perfectly encoded music, ready for playback in your portable player or Desktop music application. The only thing left, really, is to properly tag the files, but that’s a topic for another article.

One annoyance many people using laptops have discovered when first using Xfce, a popular lightweight desktop environment for Linux, is that their trackpad has the tap-to-click setting stuck “on” with no option to turn it off. Now, it should be said up front that a lot of people like tap-to-click, and if so, good for you. This article probably won’t do you a lot of good. For the rest of who at least want the option to turn off tap-to-click, here’s how to do it, and how to get the setting to stick when you restart your computer.

If you only want to turn off tap-to-click, the following command in the Terminal will do the trick:

synclient MaxTapTime=0

What this does it tell synclient to set the max tap time allowed to zero. This means in practice that any time your finger or palm touches the trackpad for longer than zero (and by definition, any touch is longer than zero), then it isn’t acknowledged as a tap. This isn’t exactly the same as turning off tap-to-click, but if your touchpad doesn’t acknowledge anything as being a tap… it’s just as good.

The problem with the above command is that it needs to be entered once per session. Log out or reboot and you’re right back to where you were before you typed it.

So what we need to do is figure out how to make that setting “stick” between boots. Not a difficult problem, as it turns out. We just need to create a little script.

So, open up a text editor. In Xubuntu, which uses Xfce as its desktop environment, Mousepad is the default text editor. It can be found in the Accessories menu, so open it from there.

Once Mousepad is open, type or paste in the following:

#!/bin/bash
# turns off tap-to-click
/usr/bin/synclient MaxTapTime=0

The first line tells the system that the following is a command that will be run in Bash, which is our standard Terminal, so running this script will be exactly the same as if we had typed it manually.

The second line is just a comment (the pound sign at the beginning of the line means it isn’t treated as a command), that reminds us what the command does. And the third line is the actual command. It’s identical to what we typed earlier, except now it has the full path to synclient.

Now save our document, by choosing the Save As option.

We’ll want to give it a memorable name; its’ really something so we remember it. Something like TapToClickFix will do.

In this image, you can see that we’ve used the name mentioned above, and have elected to save the file to our Desktop.

Now that we’ve saved the script, we need to make it executable. In other words, we need to let the system know that this script can be run as an application. To do this, first right-click on the script and select Properties.

When the Properties window appears, click on the Permissions tab and tick the checkbox at the bottom, which will allow the script to run as a program.

When you’re done, simply dismiss the window. We now need to move the script to somewhere safe. Your Home folder works well, but the script could also be places in your /usr/bin/ folder if you’d like.

Once you have the script where you want it, there’s one more step (since the script won’t run automatically). We need to add the script to the list of items that are started automatically each time you start your computer. To do this, open the Settings Manager, which can be found in the Settings Menu.

When the Settings Manager opens, click the Session and Startup icon.

When the Session and Startup window loads, click the Application Autostart tab.

Now click the Add button at the bottom of the window.

A new window will appear. This is how it looks with the necessary information filled in:

Note: When adding the information to the window as shown above, the Description really isn’t necessary. You can also choose any Name you want. The Command, on the other hand, needs to be the exact path you chose when you saved the script.

And that’s it. Restart or reboot, and you should find that tap-to-click is now turned off. If you ever decide you want it back, simply return to the Session and Startup window, and either remove the item we just added (which will remove it permanently from your startup list), or simply untick the checkbox, which will leave it in available should you change your mind once more, but won’t use it unless you tick the checkbox again.

The ‘dd’ program is one of the oldest applications in the Linux world. Originally part of UNIX, it’s generally considered to be lost to history exactly what ‘dd’ stands for. Disk Destroyer? Data Deleter? Disk Duplicator? The last option would appear to be a good bet, as either of the first two seem rather likely to scare away would-be users. Regardless, ‘dd’ is a powerful tool, and is a good go-to tool for three common use cases.

1. Backup a hard drive to a different partition or external drive.

2. Create an .iso file from a CD or DVD.

3. Make a bootable USB flash drive from a disk image.

All three of these procedures involve duplicating data from “over here” and copying it “over there,” but the different media involved (internal hard drive, external hard drive, CD and USB flash drive), would appear at first glance to require different applications. However, the ‘dd’ command can be used in all three cases.

Working With the ‘dd’ Command

There are two things to know about ‘dd’ before we start. First is that it can be incredibly dangerous to use. What ‘dd’ does is copy your data from a certain place and write it to a different place. You tell ‘dd’ where to get the data from, and where to place it.

Mix up those two places, and you’ve effectively told ‘dd’ to take data from your would-be destination drive and place it on top of the data you want to back up! Not good.

Those two parameters are ‘if‘ and ‘of‘ which stand for ‘input file’ and ‘output file.’ The ‘if’ command is generally formatted this way:

Or, if a partition is the source directory, like this:

Once we’ve told ‘dd’ where to take the data from, we need to tell it where to put the data, using the ‘of‘ option. The ‘of‘ option can be an .iso image, like this:

It could also be a disk image, like this:

There are other parameters available as well, the ‘bs’ parameter being the most widely used. This parameter represents the block size of both the input and output file, and should be a multiple of 512 (512, 1024, and 2048 are common block sizes). There are actually dozens more options, but for basic use cases, the ones already mentioned are basically all that are necessary.

Backup a Hard Drive to a Different Partition or External Drive

Let’s say you have a hard drive or partition you want to backup to an external drive, or to a different partition. This is the classic example of using the ‘dd’ command. Assuming the hard drive you want to copy data from is “/dev/sda1″ and the partition on the external hard drive you want to backup the data to is “/dev/sdc1″ the command would be as follows:

There are two parameters at the end of the basic command. We have told dd to use a block size of 4096 (larger block sizes should lead to fewer read/write cycles and generally will produce a faster backup), as well as telling it to use noerror, which will force dd to continue running, even if it encounters an error.

If you want to save the data instead to a single disk image, you would only need to modify the last part of the command:

Create an .iso File From a CD-ROM

This is a very similar command to the one just used, in that our output file is an image and not a collection of files and folders. The only big difference is that in this case, our input file is a CD-ROM or DVD-ROM disk, and not a hard drive.

In the following command, a file named cdbackup.iso will be written to our Desktop (substitute your username for “ericcflem” and you can name the .iso file whatever you want, of course):

In the above command, “conv=sync” tells ‘dd’ to use synchronized input and output, which ensures the entire block is read to protect against data loss. Depending on the speed of your drive, the process will take a few minutes, and when you’re finished, you’ll have a new .iso file that can be burned to blank media and exactly duplicate the original CD or DVD.

Make a Bootable USB Flash Drive from a Disk Image

Finally, with USB flash drives so cheap, it’s common to create a bootable flash drive for running Linux, instead of burning an actual CD. So let’s say you’ve downloaded the newest Ubuntu Live CD and want to create a bootable thumb drive. Insert the flash drive, then once it’s loaded, type the following into a Terminal window:

You’ll likely be asked for your password. Once you’ve provided it, fdisk will scan for all mounted disks. What we’re interested in is finding out the devicenode for your flash drive. Here’s example output from the above command:

As we can see, the device is /dev/sdc and the single partition is /dev/sdc1, but before we do anything, we need to unmount the partition:

Now, simply type the following command, which will copy our Ubuntu image to the entire flash drive (this command will wipe out everything on the flash drive in the process of writing the disk image):

Note also that in the above command we wrote, not to a particular partition, but to the entire drive.

And that’s it. Three different use cases, three very similar commands, one program. Using ‘dd’ isn’t as user-friendly as something like Brasero or Nero, but it is incredibly powerful. Just be careful not to mix up your input and output files, and you’ll be well on your way to making fast, accurate backups.

Ubuntu offers a nice wallpaper slideshow which cycles through outer space images every few hours, but doesn’t provide a way to customize it or create your own. Fortunately, it turns out to be pretty simple. You’ll need to get down and dirty with a little bit of XML creation, but as long as you understand the slideshow document’s XML syntax, the process goes fairly quickly.

The first step is gathering your images into a folder. You can create a slideshow from wallpapers scattered all over your hard drive, but it’s a lot easier if they’re together.

Next, open a text editor (we’re using gedit). In Ubuntu, gedit can be found under the Applications menu, then the Accessories submenu.

This will open a new document for us. Now we need to set up the XML document. Type the following tag into the new document:

Now hit Enter a couple times and type the background tag’s closing tag:

The two are identical except for the slash. The tag tells the wallpaper module that the document is a background slideshow document, while the tag tells it that the document is complete. Everything we type from here on out will be between the two tags.

Next, type the following immediately below the first tag:

2011
01
01
00
00
00

Note: from now on, items in red will be the variables you have control over, such as transition duration, file names, etc.

This tells the wallpaper module to start playing the slideshow at an exact time, in this case January 1, 2011, at midnight. In practice, since that date has already come and gone, our slideshow will start immediately after being selected. If you set the starttime tag of your slideshow sometime in the future, however, the slideshow won’t begin rotating through your images until the specified date and time.

The next tag is the tag, which looks like this:

1795.0
/home/ericcflem/ubuntu/BreezyBadger.png

Note: Substitute the path to the images in the examples to that of your own images, both here and below.

This tag contains the tag, which sets how long to display an image, and the tag, which sets the image itself. We need to use the exact path to the image, not the relative path, or it won’t work. The final tag ( in this case), closes this block of information. Also, if you want the slideshow available to all users, your images and this document should be placed in the following directory:

/usr/share/backgrounds/name-of-your-slideshow/

In this example, however, the slideshow will be placed in the home directory of a single user.

If you were curious as to why we 1795 seconds (just 5 seconds shy of 30 minutes), here’s why. The next step, the transition, is going to last for five seconds. It looks like this:

5.0
/home/ericcflem/ubuntu/BreezyBadger.png
/home/ericcflem/ubuntu/DapperDrake.png

The first and last tags ( and ) tell the screensaver that what is between them is a transition, while the tag again describes how long the transition lasts. The tag identifies which image should begin the transition and the tag tells which should end it.

In every transition, whichever image we displayed during the previous section should be the image, and our next image should be in the position.

Once you have done the previous two steps, you will alternate between new sets of and sections, until you have mapped out the entire cycle of your slideshow. In shorthand:

Your beginning Background Tag
Starttime Tag
Static Tag (for Image A)
Transition Tag (Image A to Image B)
Static Tag (Image B)
Transition Tag (Image B to Image C)
Static Tag (Image C)
Transition Tag (Image C to Image D)
Static Tag (Image D)
Transition Tag (Image D to Image A)
The final closing Background Tag

When you’re done adding images, keep in mind two things. First, the final transition should be from your final image (Image D in the above example) to your first image (Image A). This ensures that the loop, from the end back to the beginning, is a smooth one.

Second, remember the slideshow template is “finished” by adding a final tag, if necessary:

So if your document doesn’t have the tag at the very end, make sure it does before you attempt to save and use the slideshow.

To save our file, go to the File menu and choose the Save As option.

Now select a name and save location. The name can be whatever you want (but be sure to use “.xml” as the extension), then save it in the same folder as your slideshow images.

The only thing left to do now is set our new slideshow as the active wallpaper. To do so, open up the background preferences pane. Right-click on an empty part of the desktop, and select the Change Desktop Background option.

When the Appearance Pane opens to the Wallpaper tab, simply click the Add button.

Navigate in the file picker to your image folder. Make sure the settings are configured so you can see All Items (the pop-up menu in the lower right), and select the XML file we created earlier.

If everything was done correctly, you should now see your slideshow among the other wallpaper options (it looks like a little stack of images).

Click it, and your desktop should change to the first image in your slideshow, and will begin rotating through at whatever interval you set.

Okay! That’s it. To be sure, there are GUI applications that will do the same thing as we just did by hand (one can be found here), but while there’s certainly something to be said for point-and-click ease, there’s also something to be said for the understanding and experience gained from knowing how things work. Hopefully this provides the latter.