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20140611-1 选题
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HTG Explains: What’s the Difference Between Linux and BSD?
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Both Linux and the BSDs are free and open-source, Unix-like operating systems. They even use much of the same software — these operating systems have more things in common than they do differences. So why do they all exist?
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There are more differences than we can cover here, especially philosophical differences about the way one should build an operating system and license it. This should help you understand the basics, though.
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### The Basics ###
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[What most people call “Linux” isn’t actually Linux][1]. Linux is technically just the Linux kernel — typical Linux distributions are made up of many pieces of software. This is [why Linux is sometimes called GNU/Linux][2]. In fact, much of this same software on top of Linux is the same software used on the BSDs.
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Linux and the BSDs are both Unix-like operating systems. As we covered when we looked at [the history of Unix-like operating systems][3], Linux and BSD have a different lineage. Linux was written by Linus Torvalds when he was a student in Finland. BSD stands for “Berkeley Software Distribution,” as it was originally a set of modifications to Bell Unix created at the University of California, Berkeley. It eventually grew into a complete operating system and now there are multiple different BSDs.
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### Kernel vs. Complete Operating System ###
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Officially, Linux is just a kernel. [Linux distributions][4] have to do the work of bringing together all the software required to create a complete Linux OS and combining it into a Linux distribution like Ubuntu, Mint, Debian, Fedora, Red Hat, or Arch. There are many different Linux distributions.
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In contrast, the BSDs are both a kernel and an operating system. For example, FreeBSD provides both the FreeBSD kernel and the FreeBSD operating system. It’s maintained as a single project. In other words, if you want to install FreeBSD, you just install FreeBSD. If you want to install Linux, you’ll need to choose among the many Linux distributions first.
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BSDs include the ports system. which provides a way of installing software packages. The ports system contains software in source form, so your computer has to compile them before they’ll run. (If you ever used Gentoo when it was popular, it’s a bit like that.) However, packages can also be installed in pre-installed binary form so you don’t have to spend time and system resources compiling them.
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### Licensing ###
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Licensing is a significant difference, although it won’t matter to most people. Linux uses the GNU General Public License, or GPL. If you modify the Linux kernel and distribute it, you have to release the source code for your modifications.
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The BSDs use the BSD license. If you modify the BSD kernel or distribution and distribute it, you don’t have to release the source code at all. You’re free to do whatever you like with the BSD code and you’re not obligated to release the source code, although you can do so if you like.
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Both are [open-source][5], but in different ways. People sometimes get into debates about which license is “more free.” The GPL helps users by ensuring they can have the source code to GPL software, but it limits developers by forcing them to release the code. The BSD license doesn’t ensure users can have the source code, but it gives developers the freedom to do whatever they choose with the code, even if they want to turn it into a closed-source project.
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### The BSDs ###
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These are often thought of as the three “main” BSD operating systems:
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- [FreeBSD][6]: FreeBSD is the most popular BSD, aiming for high performance and ease of use. It works well on standard Intel and AMD 32-bit and 64-bit processors.
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- [NetBSD][7]: NetBSD is designed to run on almost anything and supports many more architectures. The motto on their homepage is “Of course it runs NetBSD.”
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- [OpenBSD][8]: OpenBSD is designed for maximum security — not just with its features, but with its implementation practices. It’s designed to be an operating system banks and other serious institutions would use for critical systems.
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There are two other notable BSD operating systems:
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- [DragonFly BSD][9]: DragonFly BSD was created with the design goal of providing an operating system that would run well in multithreaded environments — for example, in clusters of multiple computers.
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- [Darwin / Mac OS X][10]: Mac OS X is actually based on the Darwin operating system, which is based on BSD. It’s a bit different from other BSDs. While the low-level kernel and other software is open-source BSD code, most of the rest of the operating system is closed-source Mac OS code. Apple built Mac OS X and iOS on top of BSD so they wouldn’t have to write the low-level operating system themselves, just as [Google built Android on top of Linux][11]
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### Why Would You Choose BSD Over Linux? ###
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Linux is still more popular than even FreeBSD. Linux tends to get new hardware support before FreeBSD does, for example. The BSDs have a compatibility package available so they can natively execute Linux binaries, and most of the software works similarly.
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If you’ve used Linux, FreeBSD won’t feel all that different. Install FreeBSD as a desktop operating system and you’ll end up using the same GNOME, KDE, or Xfce [desktop environments][12] you’d use on Linux along with most of the same other software. That’s once you get to that point, though — FreeBSD won’t automatically install a graphical desktop, so you’re left to fend for yourself more than you are with modern Linux distributions. It’s a more old-school experience.
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FreeBSD may be preferred on some server operating systems for its reliability and stability. Manufacturers creating devices may choose BSD for the operating system instead of Linux so they won’t have to release the modifications to their code.
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If you’re a desktop PC user, you really don’t need to care too much about the BSDs. You’ll probably prefer Linux for its superior hardware support, easier installation, and general modern and bleeding-edge nature. If you’re putting together a server or embedded device, you may prefer FreeBSD for another reason.
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We’ll probably get comments from people who use FreeBSD on their desktop computers now, and you certainly could do so! But an operating system like Ubuntu or Mint will be more user-friendly and modern for most people.
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Image Credit: [atzerok on Flickr][13]
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--------------------------------------------------------------------------------
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via: http://www.howtogeek.com/190773/htg-explains-whats-the-difference-between-linux-and-bsd/
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译者：[译者ID](https://github.com/译者ID) 校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
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[1]:http://www.howtogeek.com/177213/linux-isnt-just-linux-8-pieces-of-software-that-make-up-linux-systems/
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[2]:http://www.howtogeek.com/139287/the-great-debate-is-it-linux-or-gnulinux/
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[3]:http://www.howtogeek.com/182649/htg-explains-what-is-unix/
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[4]:http://www.howtogeek.com/132624/htg-explains-whats-a-linux-distro-and-how-are-they-different/
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[5]:http://www.howtogeek.com/129967/htg-explains-what-is-open-source-software-and-why-you-should-care/
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[6]:http://www.freebsd.org/
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[7]:http://www.netbsd.org/
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[8]:http://www.openbsd.org/
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[9]:http://www.dragonflybsd.org/
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[10]:http://opensource.apple.com/
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[11]:http://www.howtogeek.com/189036/android-is-based-on-linux-but-what-does-that-mean/
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[12]:http://www.howtogeek.com/163154/linux-users-have-a-choice-8-linux-desktop-environments/
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[13]:http://www.flickr.com/photos/atzerok/5378691454
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Little Known Apache Mesos Project Helps Mesosphere Raise $10M From Andreessen Horowitz
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[Mesosphere][1], the company trying to build a business around the little-known open source [Apache Mesos][2] project, just racked up a $10 million investment from Andreessen Horowitz. Here’s why it attracted that kind of cash.
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Mesos, software for automatic scaling, was in fact built around five years ago and is already in use on more than 50,000 cores at Twitter, according to Florian Leibert, CEO and co-founder of Mesosphere. EBay, AirBnB, Netflix and HubSpot are also fans.
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While those big Web companies have discovered Mesos, the technology isn’t widely known among enterprises. But it could fill a need for companies which are trying to adopt some of the techniques available to them in public clouds on their internal data centers.
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Mesos manages clusters of machines, automatically scaling apps as needed. It requires a small bit of software on each machine – the software uses zero processing power and “negligible” memory, according to Liebert — which coordinates with a master scheduler. The software on each machine reports information about the capacity of the virtual machine or bare metal server to the scheduler, which allocates jobs to available machines.
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“If a task goes down and it doesn’t report back, the master knows to reschedule it and knows where it has resources,” said Matt Trifiro, senior vice president at Mesosphere.
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Mesos can automatically scale a variety of jobs including Hadoop databases, nodes running Ruby on Rails, and Cassandra.
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Using Mesos, Hubspot slashed its Amazon Web Services bill in half, said Liebert. That’s because Mesos efficiently assigns workloads to available machines.
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However, Mesos might be most appealing to businesses that are trying to essentially create an AWS-like environment internally, said Jay Lyman, an analyst at 451 Research. AWS offers some [tools for automatic scaling][3]. But many businesses are still shy about running everything on public cloud infrastructure. At the same time, they don’t want to block their developers from taking advantage of the capabilities available in public clouds like AWS. They’d like to make those capabilities available on their private clouds.
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“You’re seeing the interface of AWS-style strategy meets the old guard and command and control and stability,” he said.
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Mesos can run in both a private cloud and AWS, offering businesses the opportunity to most efficiently use their internal cloud and fallover to AWS when they need to scale.
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Mesos has some shortcomings in that regard, however. It [doesn’t run][4] any Windows or legacy apps like SAP, for instance.
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However, “if a team is contemplating cloud, they’re probably pretty deep into Linux already,” said Lyman.
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In the future, it’s possible Mesosphere could support Windows. Initially, technologies like Puppet and Chef only supported Linux too, Lyman noted. “It speaks to the early nature of Mesosphere. It’s pretty immature right now,” he said.
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Mesosphere is targeting the many enterprises that are building more and more apps running on Linux and modern programming languages as well as the first generation Web 2.0 companies like Twitter and Netflix that didn’t have technology like Mesos when they first launched. “Those are the two most common early adopter profiles,” Trifiro said.
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Before the end of the year, Mesosphere hopes to release commercial products with documentation, earning revenue from support and licensing. It has built a large-scale orchestration tool called Marathon and supports Docker integration. It’s currently offering packaged Mesos distributions for free in hopes of seeding the market.
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Mesosphere is also currently working with a handful of early customers. It helped HubSpot get going with its use of Mesos.
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Mesosphere isn’t alone in going after this use case. Rightscale, Scalr and Enstratius, now owned by Dell, all offer some version of scaling or cloud management technology. Mesosphere argues that Mesos, and the company’s own technologies, go above and beyond what’s on the market to create server clusters that essentially operate as one machine. The new investment from Andreessen could help it gain momentum.
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via: http://thenewstack.io/little-known-apache-mesos-project-helps-mesosphere-raise-10m-from-andreessen/
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译者：[译者ID](https://github.com/译者ID) 校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
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[1]:http://mesosphere.io/
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[2]:http://mesos.apache.org/
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[3]:http://aws.amazon.com/autoscaling/
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[4]:http://mesosphere.io/learn/
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Red Hat's CEO Sees Open Source Cloud Domination
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Red Hat CEO Jim Whitehurst sees the business opportunity of a generation in what he calls a computing paradigm shift from client server to cloud architectures. “In those paradigm shifts, generally new winners emerge,” says Whitehurst and he intends to make sure Red Hat is one of those winners. His logic is sound and simple: disruptive technologies like the cloud that arise every couple decades level the playing field between large, established firms and smaller, innovative challengers since everyone, from corporate behemoth to a couple guys in a garage, starts from the same spot and must play by the same unfamiliar and changeable rules. With the cloud “there’s less of an installed based and an opportunity for new winners to be chosen,” Whitehurst adds. His mission is “to see that open source is the default choice for next generation architecture” and that Red Hat is the preferred choice, particularly for enterprise IT, of open source providers.
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The case for open source dominating the cloud rests on the fact that it’s already the foundation for many popular cloud services and enterprise applications. Whitehurst aptly notes that outside of Microsoft Azure, the underlying infrastructure of all the major public cloud services is built upon open source software. Furthermore, software like Linux, Apache, MySQL, WordPress and many others are already widely used and trusted by most enterprises. “In many cases [open source] already is the default choice for next generation architectures, but it hasn’t fully driven itself through the traditional enterprise data center,” he says. Cloud software is the next and most important software category up for open source disruption.
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Yet open source is still saddled with a reputation for widely variable software quality and support, something the recent OpenSSL Heartbleed bug only reinforced. However Whitehurst contends that strong enterprise adoption of Red Hat’s Linux distribution and it’s training and skills certification programs lends credibility to a similar plan for the cloud: [Red Hat’s Cloud Partner Program][1]. He believes such insurance policies alleviate enterprise IT’s fears of adopting open source software for both internal, private clouds and external public cloud services. Red Hat wants its imprimatur to be the Good Housekeeping seal of approval for open source in general and cloud software in specific, namely IT’s assurance that their applications will work and the service is trustworthy and reliable.
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Red Hat’s strategy to make open source clouds safe for the enterprise is mirrors that used to break into the market for enterprise server software. There, “Job one for Red Hat is making sure our operating system and layers above that work well on anyone’s infrastructure underneath,” says Whitehurst. Red Hat is applying this same model of polishing, integrating and supporting open source software to cloud stacks. “One of the most important parts about cloud, public, private or hybrid, is a sense that you can confidently run your applications,” says Whitehurst and he believes Red Hat’s track record on Linux and other open source products will carry over to make Red Hat “the enterprise choice” for cloud architectures.
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### Cloud isn’t just virtualization 2.0 ###
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One of the conundrums for OpenStack advocates like Whitehurst is the entrenchment of Microsoft and VMware in the enterprise market. Although virtual servers are a prerequisite for clouds, they’re sufficient. Countering the notion that enterprise clouds are just a natural extension of virtualized servers and storage, Whitehurst argues that by setting new rules for infrastructure and application design, cloud infrastructure is more than just the natural evolution of server virtualization.
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Whitehurst draws an important distinction between traditional client-server and cloud-optimized applications. “One of the big questions will be how much of this [cloud adoption] is moving traditional Windows workloads, which frankly were written as stateful apps in the first place. [Instead] are we talking about a new generation of applications that are actually built with elasticity and scalability in mind.” Whitehurst clearly believes cloud infrastructure is much more appropriate for the latter and that in such Greenfield scenarios, OpenStack and other open source software have established themselves as the preferred platform. Contrasting OpenStack, based on the Linux KVM hypervisor and VMware or Microsoft using their proprietary virtual machine platforms, Whitehurst says, “Longer term, nobody really cares what the hypervisor is, you just expect it to work and bluntly, as long as Red Hat supports you on it, why do you have to care,” adding “more and more, you’ll see the hypervisor mattering less and less.” Of course, VMware and Microsoft probably agree, both having moved their energies to building more sophisticated management platforms and making the hypervisor a baseline feature.
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But in Whitehurst’s view of the world, traditional virtualization platforms like VMware or Microsoft Hyper-V are legacy infrastructure designed for yesterday’s client-server software, not the sort of distributed, rapidly relocatable, elastically scalable applications that define the era of big data, SaaS and social software. “I’m not sure what good you get out of putting Exchange on a cloud,” he quips. Instead, he says this new generation of cloud-optimized applications are the sweet spot for OpenStack. According to Whitehurst, “If you look at where most new applications are getting built, and therefore where so much of the innovation around languages, frameworks and management paradigms are happening, it’s around an open infrastructure.” But there’s obviously some selection bias in Whitehurst’s account, as he lives in an open source world where it’s easy to be unaware, overlook or ignore the innovation happening on proprietary cloud platforms like Azure, AWS and vCloud.
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In sum, Whitehurst hopes and expects OpenStack to do to VMware what Linux did to Windows: to become the first choice of cloud-savvy startups and if not the default choice, at least an accepted and respectable alternative within the enterprise. In my next column I’ll explain that even for an open source champion like Whitehurst, OpenStack versus VMware vCloud or Microsoft Azure isn’t an either/or choice and how he sees the fundamental notion of cloud computing as based on virtual machines as an design model likely to change.
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--------------------------------------------------------------------------------
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via: http://www.forbes.com/sites/kurtmarko/2014/06/08/red-hat-ceo-open-source-clouds/
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译者：[译者ID](https://github.com/译者ID) 校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
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[1]:http://www.redhat.com/partners/become/cloud/
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How to Prevent Other Users From Accessing Your Home Directory in Ubuntu 14.04
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If you share your Ubuntu machine with other people, you probably have multiple users set up, thinking that the other users log into their own accounts and only have access to their own home directories. However, by default, any user can access any home directory.
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When you add a new user in Ubuntu, the adduser utility creates a new home directory for the new account. By default, the new home directory is placed in the /home/ directory on the root followed by the username. For example, /home/lori. User home directories in Ubuntu are created with world read/execute permissions, giving all other users on the system rights to read the contents of other users’ home directories. See our article for more information about [how file permissions work in Linux][1].
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**NOTE**: When we say to type something in this article and there are quotes around the text, DO NOT type the quotes, unless we specify otherwise.
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You can easily change the permissions for your home directory to protect your private files. To check the permissions on your home directory, press Ctrl + Alt + T to open a Terminal window. Type the following line at the prompt and press Enter. Replace “<username>” with your own username.
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ls –ld /home/lori
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**NOTE**: The command contains only lowercase L’s not the number 1.
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At the beginning of the line, the permissions for the file are listed. As said in our [article][1] about Linux permissions:
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> “The r stands for “read,” the w stands for “write,” and the x stands for “execute.” Directories will start with a “d” instead of a “-“. You’ll also notice that there are 10 spaces which hold value. You can ignore the first, and then there are 3 sets of 3. The first set is for the owner, the second set is for the group, and the last set is for the world.”
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So, the home directory listed below has read, write, and execute permissions for the owner and read and execute permission for the group and world.
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To change these permissions, type the following line at the prompt and press Enter.
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sudo chmod 0750 /home/lori
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Type your password when prompted and press Enter.
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**NOTE**: The chmod command uses octal numbers as one way to indicate permissions. Our [article][1] about Linux file permissions uses a different method that requires more steps but may be easier to understand. Using the octal numbers to specify permissions is a quicker method. Use whichever method with which you are more comfortable. To learn about using octal numbers to set permissions, see this [article][2].
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Press the up arrow twice to use the “ls –ld /home/<username>” command again to check the permissions. Notice that the permissions for world are all dashes (-). That means that the world cannot read, write, or execute anything in your home directory.
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However, users in the same group as you can read and execute files and folders in your home directory. If you don’t want anyone else but yourself to have access to your home directory, enter “0700” as the numbers in the chmod command.
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**NOTE**: For more information about managing users and groups in Linux, see our [article][3].
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To close the terminal window, type “exit” at the prompt and press Enter.
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Now, when other users on the system try to access your home directory, the following dialog box displays.
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You can also set up Ubuntu to use specific permissions when setting up the home directory for a new user you are creating. To do this, you need to edit the adduser configuration file. To do this, type the following command at the prompt and press Enter.
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gksudo gedit /etc/adduser.conf
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We are using gedit to edit the file. You can use a different text editor if you want.
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NOTE: The gksudo command is like the sudo command but is used to run graphical programs as root. The sudo command is used to run command line programs as root.
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Enter your password in the Password edit box on the dialog box that displays and press Enter or click OK.
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Scroll down to the DIR_MODE command in the adduser.conf file. The number set is “0755” by default. Change it to reflect the different types of permissions (r, w, x) you want to grant to the different types of users (owner, group, world), such as “0750” or “0700” as discussed earlier. Click Save.
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Close gedit by selecting Quit from the File menu. You can also click the X button in the upper-left corner of the window to close gedit.
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Close the Terminal window by clicking the X in the upper-left corner of the window.
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Now, the files in your home directory will remain private. Just remember that, if there are other users in the same group as you, you might want to take away the permissions for both group and world for your home directory.
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via: http://www.howtogeek.com/190084/how-to-prevent-other-users-from-accessing-your-home-directory-in-ubuntu-14.04/
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译者：[译者ID](https://github.com/译者ID) 校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出
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[1]:http://www.howtogeek.com/67987/htg-explains-how-do-linux-file-permissions-work/
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[2]:http://www.linux.org/threads/file-permissions-chmod.4094/
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[3]:http://www.howtogeek.com/howto/36845/the-beginners-guide-to-managing-users-and-groups-in-linux/
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