Start the Sound Preferences dialog box by selecting System -> Preferences -> Sound from the top Panel menu. The Sound Preferences utility starts. The Sound Preferences dialog box has two tabs of settings:

• Devices: Allows you to select which sound system to use for specific audio functions.

• Sounds: Allows you to select specific sounds for specific system functions. Each tab controls the settings for specific features of the sound environment.


The Devices Tab
The Devices tab sets the default front-end sound system used for the different types of sound generated on the workstation

For each category of sounds, you can select the front-end sound management system to use. Ubuntu includes three software sound management packages:
• The Advanced Linux Sound A Architecture (ALSA)
• The Open Sound System (OSS)
• The PulseAudio Sound Server

By default Ubuntu will set the values to autodetect the best sound system for your workstation. You can change the selected sound management system by clicking the drop-down box for the sound generation method and selecting the sound management system you want to use. The Audio Conferencing setup allows you to select separate sound management systems for playing received sound and recording sound to send.


The Sounds Tab
The Sounds tab provides an interface for you to select various sounds for Ubuntu to play
for specific system events. Figure 11-2 shows the events that you can define sounds for.
For each event you can select to play the default sound, disable the sound, or select a
custom sound from a sound file. The only restriction is that the sound file must be in WAV format.


The Sound Applet
When Ubuntu detects a sound card in your workstation at installation time, it automatically places the Sound applet in your panel. The Sound applet appears as a speaker icon in the right side of the top panel. When you click it, the master volume control appears.

The slider allows you to set the overall volume level of the workstation speakers. For more detailed volume control, double-click the Sound applet icon, and the ALSA mixer windowrs.

The ALSA mixer contains eight sets of sliders for detailed control of the sound environment:
• Master: Controls the overall volume level of the mixer (this is the same as the master volume control that appears if you single-click the icon).
• Headphone: Controls the volume level for the headphone jack on the workstation.
• PCM: Controls the volume level for audio CDs and music files when played from the system.
• Front: Controls the volume level for the speakers on the workstation, either internal or external.
• Line-in Boost: Sets the recording level for an external microphone plugged into the microphone jack on the workstation.
• CD: Sets the left and right channel volume when playing audio CDs.
• Microphone: Sets the recording level for the built-in microphone on the workstation.
• PC Speaker: Sets the volume for the built-in speaker on the workstation.
Using these sliders you can customize the sound volume for playing and recording audio from all applications on your workstation.

Source of Information : OReilly Linux in a Nutshell 6th Edition

To Unix systems, a filesystem is a device (such as a partition) that is formatted to store files. Filesystems can be found on hard drives, floppies, CD-ROMs, USB drives, or other storage media that permit random access.

The exact format and means by which the files are stored are not important; the system provides a common interface for all filesystem types that it recognizes. By default, almost all modern distributions of Linux use a journaling filesystem. When the kernel interacts with a journalling filesystem, writes to disk are first written to a log or journal before they are written to disk. This slows down writes to the filesystem, but reduces the risk of data corruption in the event of a power outage. It also speeds up reboots after a system unexpectedly loses power.

Most current Linux distributions default to the Third Extended (ext3) Filesystem. The ext3 filesystem was developed primarily for Linux and supports 256-character filenames and 4-terabyte maximum filesystem size. This ext3 filesystem is essentially a Second Extended (ext2) filesystem with an added journal. Since it is in all other ways identical to the ext2 system, it is both forward- and backward-compatible with ext2—all ext2 utilities work with ext3 filesystems.

Although not covered in this edition of Linux in a Nutshell, Linux supports other open source journaling filesystems including: IBM’s Journaled Filesystem (JFS), SGI’s Extensible Filesystem (XFS), and the Naming System Venture’s Reiser Filesystem (ReiserFS). In some situations these can be faster than ext3. Some Linux distributions use these alternative filesystems by default. Other common filesystems include the FAT and VFAT filesystems, which allow files on partitions and floppies of Microsoft Windows systems to be accessed under Linux, and the ISO 9660 filesystem used by CD-ROMs.



Common Command about Managing Filesystems

debugfs Debug ext2 filesystem.
dosfsck Check and repair a DOS or VFAT filesystem.
dump Back up data from a filesystem.
dumpe2fs Print information about superblock and blocks group.
e2fsck Check and repair an ext2 filesystem.
e2image Store disaster-recovery data for an ext2 filesystem.
e2label Label an ext2 filesystem.
edquota Edit filesystem quotas with vim.
fdformat Format floppy disk.
fsck Another name for e2fsck.
fsck.ext2 Check and repair an ext2 filesystem.
mke2fs Make a new ext2 filesystem.
mkfs Make a new filesystem.
mkfs.ext2 Another name for mke2fs.
mkfs.ext3 Yet another name for mke2fs.
mklost+found Make lost+found directory.
mkraid Set up a RAID device.
mkswap Designate swapspace.
mount Mount a filesystem.
quotacheck Audit stored quota information.
quotaon Enforce quotas.
quotaoff Do not enforce quotas.
quotastats Display kernel quota statistics.
rdev Describe or change values for root filesystem.
repquota Display quota summary.
resize2fs Enlarge or shrink an ext2 filesystem.
restore Restore data from a dump to a filesystem.
rootflags List or set flags to use in mounting root filesystem.
setquota Edit filesystem quotas.
showmount List exported directories on a remote host.
swapoff Cease using device for swapping.
swapon Begin using device for swapping.
sync Write filesystem buffers to disk.
tune2fs Manage an ext2 filesystem.
umount Unmount a filesystem.
warnquota Mail disk usage warnings to users.


Source of Information : OReilly Linux in a Nutshell 6th Edition

Some distributions contain the source code for Linux; it is also easily available for download at http://www.kernel.org and elsewhere. Source code is similarly available
for all the utilities on Linux (unless your vendor offers a commercial application or library as a special enhancement). You may never bother looking at the source code, but it’s key to Linux’s strength. Under the Linux license, the source code has to be provided or made available by the vendor, and it permits those who are competent at such things to fix bugs, provide advice about the system’s functioning, and submit improvements that benefit everyone. The license is the GNUproject’s well-known General Public License, also known as the GPL or “copyleft,” invented and popularized by the Free Software Foundation (FSF).

The FSF, founded by Richard Stallman, is a phenomenon that many people might believe to be impossible if it did not exist. (The same goes for Linux, in fact—20 years ago, who would have imagined a robust operating system developed by collaborators over the Internet and made freely redistributable?) One of the most popular editors on Unix, GNU Emacs, comes from the FSF. So do gcc and g++ (C and C++ compilers), which for a while set the standard in the industry for optimization and the creation of fast code. One of the most ambitious projects within GNUis the GNOME desktop, which encompasses several useful generalpurpose libraries and applications that use these libraries to provide consistent behavior and interoperability.

Dedicated to the sharing of software, the FSF provides all its code and documentation on the Internet and allows anyone with a whim for enhancements to alter the source code. One of its projects is the Debian distribution of Linux.

To prevent hoarding, the FSF requires that the source code for all enhancements be distributed under the same GPL that it uses. This encourages individuals or companies to make improvements and share them with others. The only thing someone cannot do is add enhancements, withhold the source code, and then sell the product as proprietary software. Doing so would be taking advantage of the FSF and users of the GPL. You can find the text of the GPL in any software covered by that license, or online at http://www.gnu.org/copyleft/gpl.html.

As we said earlier, many Linux tools come from BSD instead of GNU. BSD is also free software. The license is significantly different, but that probably doesn’t concern you as a user. The effect of the difference is that companies are permitted to incorporate the software into their proprietary products, a practice that is severely limited by the GNU license.

Source of Information : OReilly Linux in a Nutshell 6th Edition

Linux is, first of all, free software: anyone can download the source from the Internet or buy it on a low-cost CD-ROM. But Linux is becoming well known because it’s more than just free software—it’s unusually good software. You can get more from your hardware with Linux and be assured of fewer crashes; even its security is better than many commercial alternatives.

Linux first appeared in organizations as ad hoc installations by hackers running modest web servers or development systems at universities and research institutions, but it now extends deeply into corporations around the world. People deploying Linux for mission-critical systems tend to talk about its ample practical advantages, such as the ability to deliver a lot of bang for the buck and the ease of deploying other powerful tools on Linux, such as Apache, Samba, and Java environments. They also cite Linux’s ability to grow and sprout new features of interest to large numbers of users. But these advantages can be traced back to the concept of software freedom, which is the root of the broad wave of innovation driving Linux.

As free software, Linux revives the grand creativity and the community of sharing that Unix was long known for. The unprecedented flexibility and openness of Unix—which newcomers usually found confusing and frustrating, but eventually found they couldn’t live without—continually inspired extensions, new tools, and experiments in computer science that sometimes ended up in mainstream commercial computer systems.

Many programmers fondly remember the days when AT&T provided universities with Unix source code at no charge and the University of Berkeley started distributing its version in any manner that allowed people to get it. For these older hackers, Linux brings back the spirit of working together—all the more so because the Internet is now so widespread. And for the many who are too young to remember the first round of open systems or whose prior experience has been constricted by trying to explore and adapt proprietary operating systems, now is the time to discover the wonders of freely distributable source code and infinitely adaptable interfaces.

The economic power behind Linux’s popularity is its support for an enormous range of hardware. People who are accustomed to Microsoft Windows are often amazed at how much faster their hardware appears to work with Linux—it makes efficient use of its resources.

For the first several years after its appearance, users were attracted to Linux for a variety of financial and political reasons, but soon they discovered an unexpected benefit: Linux works better than many commercial systems. With the Samba file and print server, for instance, Linux provides stable Windows-based networking to a large number of end-user PCs. With the Apache web server, it provides more of the useful features web administrators want than competing products do. Embedded versions of the Linux kernel are growing in use because, although they are larger than the most stripped-down operating systems, they deliver a range of powerful features within a remarkably small footprint.

Opinions still differ on how suitable Linux is as a general-purpose desktop system. But the tremendous advances in usability and stability of the desktop software and its applications are undisputed. Soon (if not today), one will find Linux in many offices and other end-user environments. Meanwhile, the strides made by Linux in everyday computing tasks are reflected in the many new commands found in this edition.

Source of Information : OReilly Linux in a Nutshell 6th Edition

P2P (peer-to-peer) is the nature of the Net. You can fight that, or you can embrace it. Here in the US, the mainstream entertainment business has mostly been fighting it. Hollywood and its phone and cable company allies have long regarded P2P, and BitTorrent in particular, as a copyright piracy system and a bandwidth hog. In the European Union, however, P2P is more than accepted: it’s supported by the Union itself.

Early last year, the EU granted 14 million euros to P2P-Next, a consortium of 21 media companies and universities, including the BBC, Delft University of Technology, the European Broadcasting Union, Lancaster University, Markenfilm, Pioneer Digital Design Centre Limited and VTT Technical Research Centre of Finland. The purpose of the grant is “to develop a Europe-wide ’next-generation’ Internet television distribution system, based on P2P and social interaction”. (An additional 5 million euros is also being donated by some of the P2P-Next partners, for a total of 19 million euros.) The project has a four-year span and will include technical trials of new media applications on many devices.

“Everything we’re doing is based on open source”, says Johan Pouwelse, PhD, scientific director of P2P-Next and Assistant Professor of Computer Science at Delft. The good doctor also runs P2P-Next’s first trial application: Tribler (pronounced “tribe-ler”), a BitTorrent-based client with no servers and a “zero-cost” business model. Tribler provides an all-in-one way to find, consume and share media.

But Tribler goes beyond BitTorrent to support live streaming and other enhancements. The project’s Research page lists 26 allied development projects, including six that are already completed and operational. If you’re looking to help media evolve past the TV model, there’s a rich pile of possibilities on the Tribler project list. The Tribler download page lists two Linux sources: Ubuntu Linux and “GNU+Linux/Source”.

Check it out, and let us know how it works for you (or, you for it).

• 19 Million Euro for P2P Research:
www.tribler.org/P2P-Next/
19Million-for-P2P

• P2P Next: www.p2pnext.org/?page=content&id=264A360A217FB3FE8BD82CB9C928CBCF&mid=6BED2EAC3D127503EF53456A25D9204E

• Tribler: www.tribler.org

• Tribler Research Page: www.tribler.org/TriblerResearchSubjects

• Tribler Download Page:
www.tribler.org/Download

Source of Information : Linux Journal Issue 177 January 2009

Cloud computing from the likes of Google and Amazon has become quite the rage in the last few years. Nick Carr’s The Big Switch and other works have pointed toward a future of “utility” computing where we’ll all use hosted apps and storage, thanks to the “scale” provided by big back-end companies and their giant hardware and software farms. But, there also has been pushback. Most notable among the nay-sayers is Richard M. Stallman, who calls it “worse than stupidity” and “a trap”.

At issue is control. Of Web apps, RMS says, “It’s just as bad as using a proprietary program. Do your own computing on your own computer with your copy of a freedom-respecting program. If you use a proprietary program or somebody else’s Web server, you’re defenseless. You’re putty in the hands of whoever developed that software.”

We wrote about it on-line at LinuxJournal.com, and among the many comments was one that pointed to eyeOS: a cloud computing approach by which people can make their own clouds: “...all you need is a Web server that supports PHP and OpenOffice.org to get the most out of the included office suite”, the commenter said. “It’s cloud computing, but at the same time you still have control over your data.”

eyeOS is based in Barcelona, and obviously, it doesn’t believe you need to be a Google or anyone special to run a “cloud” Web service environment. Unlike Google’s cloud, you don’t need to run the eyeOS’s hosted apps. You can upload your own or choose ones from eyeOS or other developers. The UI is a virtual desktop, inside a browser (just as with Google), and the initial suite of apps are the straightforward set you’d expect, plus many more. These come with user ratings and a very active set of forums for developers and users.

eyeOS is a commercial company, privately held (and debt-free, it says). Its business model is service and support. If you need help installing eyeOS or adapting apps for your company, they’re available.

• Stallman vs. Clouds:
www.linuxjournal.com/content/
stallman-vs-clouds

• eyeOS: eyeos.com/en

• eyeOS Blog: blog.eyeos.org

Source of Information : Linux Journal Issue 177 January 2009