OpenWrt is a community driven example upon which many of the OEM firmware releases are based. In the non-mobile telecommunications equipment sector, the majority of customer-premises equipment (CPE) hardware runs some Linux-based operating system. Due to its low cost and ease of customization, Linux is often used in embedded systems.
The performance of Linux on the desktop has been a controversial topic;[citation needed ] for example in 2007 Con Kolivas accused the Linux community of favoring performance on servers. He quit Linux kernel development out of frustration with this lack of focus on the desktop, and then gave a “tell all” interview on the topic.  Since then a significant amount of development has focused on improving the desktop experience. Projects such as Upstart and systemd aim for a faster boot time; the Wayland and Mir projects aim at replacing X11 while enhancing desktop performance, security and appearance.
 Initially, nobody registered it, but on August 15, 1994, William R. Torvalds has stated that he trademarked the name only to prevent someone else from using it. In 1996, Torvalds and some affected organizations sued him to have the trademark assigned to Torvalds, and, in 1997, the case was settled.  The licensing of the trademark has since been handled by the Linux Mark Institute (LMI). Filed for the trademark Linux, and then demanded royalties from Linux distributors. In the United States, the name Linux is a trademark registered to Linus Torvalds. LMI originally charged a nominal sublicensing fee for use of the Linux name as part of trademarks, but later changed this in favor of offering a free, perpetual worldwide sublicense.
As of May 2011[update], about 8% to 13% of a modern Linux distribution is made of GNU components (the range depending on whether GNOME is considered part of GNU), as determined by counting lines of source code making up Ubuntu’s “Natty” release; meanwhile, 6% is taken by the Linux kernel, increased to 9% when including its direct dependencies.
They also include tools for administering and building school computer labs and computer-based classrooms, such as the Linux Terminal Server Project (LTSP). The Ubuntu derivatives Edubuntu and The Linux Schools Project, as well as the Debian derivative Skolelinux, provide education-oriented software packages.
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In addition, Windows was used as an operating system on non-mission critical systems—laptops used on board the space station, for example—but it has been replaced with Linux; the first Linux-powered humanoid robot is also undergoing in-flight testing.
Guile Scheme acts as an extension language targeting the GNU system utilities, seeking to make the conventionally small, static, compiled C programs of Unix design rapidly and dynamically extensible via an elegant, functional high-level scripting system; many GNU programs can be compiled with optional Guile bindings to this end. While not as common, Linux also supports C# (via Mono), Vala, and Scheme. A number of Java Virtual Machines and development kits run on Linux, including the original Sun Microsystems JVM (HotSpot), and IBM’s J2SE RE, as well as many open-source projects like Kaffe and JikesRVM. Most distributions also include support for PHP, Perl, Ruby, Python and other dynamic languages.
Org implementation of the X Window System uses the MIT License.  Other key components of a typical Linux distribution are also mainly licensed under the GPL, but they may use other licenses; many libraries use the GNU Lesser General Public License (LGPL), a more permissive variant of the GPL, and the X. Linux kernel is licensed under the GNU General Public License (GPL), version 2. The GPL requires that anyone who distributes software based on source code under this license, must make the originating source code (and any modifications) available to the recipient under the same terms.
Profession-specific distributions include Ubuntu Studio for media creation and DNALinux for bioinformatics. Certain organizations use slightly specialized Linux distributions internally, including GendBuntu used by the French National Gendarmerie, Goobuntu used internally by Google, and Astra Linux developed specifically for the Russian army. There is also a Muslim-oriented distribution of the name Sabily, as well as an Arabic-focused distribution called Ojuba Linux that consequently also provides some Islamic tools. Such examples include Ubuntu Kylin for Chinese language users and BlankOn targeted at Indonesians. There are general-purpose Linux distributions that target a specific audience, such as users of a specific language or geographical area.
Red Hat Enterprise Linux 4 Reference Guide For Red Hat Enterprise Linux 4 Edition 4 Red Hat Inc.
Michael Jang, RHCSA/RHCE Red Hat Linux Certification Study Guide, McGraw- . This guide was originally named Linux & LPIC Quick Reference Guide, then.