25+ Awesome Linux/Unix command chaining examples

By

Surendra Anne

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March 15, 2016

Command chaining is a concept to execute two or more commands in one execution to increase.

productivity

Reduce system resource usage (In some cases)

Short and sweet codes.

These are supported by almost every shell we know.

Today we will learn how to use different command chaining operators available for us in an easy way.

Command chaining operators

& --Sends process background (so we can run multiple process parallel); --Run multiple commands in one run, sequentially.
	 --To type larger command in multiple lines
	&& --Logical AND operator
	|| --Logical OR operator
	! -NOT operator ( Thanks for 
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  for giving good examples)
	| -- PIPE operator
	{} --Command combination operator.
	() --Precedence operator

& – Runs a command in the background

This operator is useful to send a process/script/command to background, so that we can execute other commands in foreground to increase effective utilization of system resources and to speed up the script execution. This is also called as Child process creation or forking in other programming languages.

Example 1: Run commands in the background

$ping -c1 google.com &

Example 2: Run more commands in the background in single line $

ping -c1 google.com & scp 
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 :/opt/* /opt &

Above commands are run in the background parallel independent of other commands. Like this, we can run many commands parallel.

; – semicolon operator

This operator Run multiple commands in one go, but in a sequential order. If we take three commands separated by semicolon, second command will run after first command completion, third command will run only after second command execution completes. One point we should know is that to run second command, it do not depend on first command exit status.

Example 3: Execute ls, pwd, whoami commands in one line sequentially one after the other.

ls;pwd;whoami

Note: The number of commands you can run is infinity as we said earlier. By default there is no limit on how many commands you can run with ; operator. We have checked this with 500 commands executed in one line. The limit depends only on memory or ulimits settings.

Read Full Post: http://www.linuxnix.com/23-awesome-less-known-linuxunix-command-chaining-examples/

Mozilla will Emit “First Version” of Servo-Based Rust Browser in June

By

The Register

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March 15, 2016

Mozilla is planning an initial release of its new Servo-based new web browser in June, according to a post on the developer mailing list by research engineer Paul Rouget,

“Release” in this context does not suggest a production-ready download, but rather an early preview.

Rouget states his wish for Servo “to be capable of running github, duckduckgo, hackernews and reddit,” adding that “we’re close, but there are still several rendering and functional issue for each of these websites.” Servo is a cross-platform browser engine that will run on ARM operating systems (including Android) as well as on x64 platforms including Linux, OS X and Windows….

Getting Started With OpenStack: Your Questions Answered

By

Amber Ankerholz

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March 15, 2016

Blog OpenStack 200x200 v2 Adoption of OpenStack, the open source cloud platform, continues to grow but challenges do remain. Although many enterprise companies have taken the leap, a recent SUSE report indicates that a lack of skilled IT professionals is making other organizations reluctant to implement OpenStack.

To help you learn more about OpenStack and determine whether it’s the right choice for your organization, we recently produced “Getting Started with OpenStack,” a free webinar with Tim Serewicz, who teaches OpenStack and Linux performance and tuning courses for The Linux Foundation. In the webinar, Tim addressed some of the most common OpenStack questions and concerns, such as:

I think I need OpenStack, but where do I start?
What problems does OpenStack solve?
What are the hurdles?
Why is it worth the effort?

However, more than 100 additional questions were submitted during the webinar, so we followed up with Tim to provide more answers. Many of the questions overlapped in theme, so we’ve grouped them here into eight general questions summarizing the main topics.

Question 1: Can OpenStack be integrated with other solutions, such as AWS (Amazon Web Services)?

Answer: Yes. OpenStack has been developed to work with other cloud providers. The ability to maintain a smaller private cloud that can easily scale through a private/public connection, or to meet temporary demand for resources, is very attractive to new business projects. While more expensive in the short term, using a metric like CPU-hour, the overall cost of access to resources is much lower.

Currently, AWS is the largest public cloud provider and seems to be the focus for compatibility, but other options exist. Because OpenStack is an open source project, new connections can be easily implemented.

Question 2: How does OpenStack compare to other technologies?

Answer: OpenStack provides Infrastructure as a Service (Iaas), of which there are other open and proprietary options. In the open source area, OpenStack has been widely implemented. The number of developers is second only to the Linux kernel. With so much effort and attention being given, it has become the best choice for production. Other open source projects, in contrast, may lack the development and use necessary to discover and fix issues. Several small and large technology companies offer support for OpenStack, removing vendor lock-in while maintaining dedicated support.

There are several proprietary cloud, or cloud-like, solutions available. When unable to view or change the software, a user becomes locked into working with the vendor in addition to paying high license fees. If a new feature is necessary or an issue is discovered, the user can only make a request and hope something will be done in a timely manner, if done at all.

Question 3: What are the options for high availability (HA) with OpenStack?

Answer: This area of OpenStack is under a lot of development. With a distributed cloud architecture, many users find they don’t need to have HA as they did with traditional vendor products, and implement an HA database like Galera with MariaDB and a load balancer to avoid loss of access to cloud services after a failure.

You can achieve full HA with open solutions, but there is not currently an easy-to-use or implement procedure. Most of the full HA solutions currently in production are third party and proprietary.

Question 4: What’s the link between Linux and OpenStack?

Answer: OpenStack is an open source federation of software projects to provide infrastructure as a service. It was developed on Linux. Just as there are several Linux distributions using the same open source code, there are several OpenStack distributions. OpenStack can work with other operating systems for compute hosts, but the vast majority of nodes will be running some flavor of Linux.

Question 5: How does software-defined networking (SDN) relate to OpenStack?

Answer: OpenStack provides IasS so users can virtualize every aspect of a datacenter. Networking is a big part of any datacenter. The Neutron project provides SDN, which one can use to configure networking equipment — open or proprietary. The OpenDaylight platform is one possible SDN option, which aims to remove proprietary software on network equipment and which includes support for a wide range of network protocols and an ease for adding new functionality.

The OpenDaylight project has some overlap with OpenStack. OpenStack is focused on virtualization and automation, whereas OpenDaylight is focused on decoupling the control plane of the network. Both projects are actively developed and will most likely become more complementary.

Question 6: What are the security implications of OpenStack?

Answer: Security is an area which has not had as much attention as other projects. OpenStack potentially has the same exposure as a traditional datacenter. Often, an OpenStack deployment was not exposed to Internet traffic, and security was handled exterior to the cloud. New projects have been created to handle various issues, such as Congress for policy enforcement. A good place to start looking at security is with the OpenStack security guide.

Question 7: What are the hardware/environment requirements for OpenStack?

Answer: OpenStack can be deployed in many different ways, and can scale up as necessary. Even small shops, or home use, can benefit. While it can run on even small VMs it may not be very fast. The “How To Get Started With OpenStack” guide is a good place to see some of your options. DevStack easily runs in a VM, and the “All-In-One Single VM” guide provides the steps for doing so.

Question 8: What is the relationship between VMware, virtualization, and OpenStack?

Answer: OpenStack uses virtualization and automation to provide IaaS. It supports a large number of hypervisors including KVM, Hyper-V, LXC, and VMware. You could use it with VMware or to replace VMware — among other proprietary vendors. Because OpenStack can manage VMware resources, it is quite easy to grow your OpenStack cloud and transition so that eventually you no longer need any VMware licenses.

The original OpenStack webinar can be seen in its entirety through The Linux Foundation’s online webinar portal (registration is required).

To learn even more about OpenStack, check out the following Linux Foundation training courses:

OpenStack Administration Fundamentals (online, self-paced)

Essentials of OpenStack Administration (live instructor-led)

How to use Port Knocking on Ubuntu to hide the SSH port

By

Falko Timme

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March 15, 2016

You all know these old gangster films where a guy uses a knock sequence on a door to get in? Port Knocking is exactly that, just for your server. Installing port knocking on Ubuntu is easy. I will show you in this article how to install and set up port knocking. The steps from this tutorials should work for Debian 8 as well.

Researchers Trace Android Malware Back to Common Sources

By

eWeek

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March 15, 2016

The code for a number of malicious Android programs suggest a common source, whether a developer or competing groups, according to a pair of analyses from IBM and FireEye.

Code analysis has established a link between a number of malicious Android programs, suggesting that they are likely the work of a single developer or the product of code sharing—whether intentional or inadvertent, according to a report published by security company FireEye on March 11.

Google Announces New Tools for Game Developers

By

The Linux Foundation

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March 15, 2016

nexus2cee 2016-03-15-06.29.10-728x613 At GDC, Google announced a few new game-focused tools for developers that should make launching, promoting, and monetizing titles easier. There’s now a full blog post on the changes, and they look like a big deal for developers, especially those who consider themselves”indie.”

Google is launching a new collection in the Play Store that it will promote via banners and links called the Indie Corner. As the name suggests, it’s a list of games created by indie devs.

AWS Ready to Launch Database Migration Service

By

The Linux Foundation

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March 15, 2016

Amazon Web Services will today launch its AWS Database Migration Service, reports have claimed. The service, which helps companies move massive databases onto Amazon Web Services, has been in preview since last October, but AWS now reportedly thinks it is ready for a full public launch, according to the Wall Street Journal.

It can take months or years for a large company to move the entirety of its databases to the cloud, and last year AWS launched a physical storage device called the Snowball, to help customers shift large data sets around quickly.

Canonical Releases Major Kernel Update for Ubuntu 14.04 LTS, Patches 13 Issues

By

Softpedia

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March 15, 2016

canonical-releases-major-kernel-update We reported on March 14 that Canonical published two new Ubuntu Security Notices with detailed information on multiple Linux kernel vulnerabilities patched for Ubuntu 12.04 LTS (Precise Pangolin) and and Ubuntu 15.10 (Wily Werewolf) operating systems.

Today, March 15, 2016, we’re informing you about a major kernel update for the Ubuntu 14.04 LTS (Trusty Tahr) operating system, for which Canonical patched no less than thirteenth vulnerabilities discovered by various developers and hackers.

We recommend reading the Ubuntu Security Notice USN-2929-1 bulletin if you want to know what exactly has been patched…

Can DevOps and ITIL Co-Exist? A Story of Two IT Service Philosophies

By

ZDNet

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March 15, 2016

Is ITIL, first formulated more than two decades ago to promote service-thinking within IT ranks, a good fit within emerging DevOps cultures? Can ITIL and DevOps co-exist?

That’s the question recently put forth by Gareth Daine, who quizzed some 25 industry experts and observers on whether the two methodologies clash, or are compatible. ITIL, originally known as Information Technology Infrastructure Library, is a set of best practices which recognize and certify that IT functions are delivered as tangible services to organizations. DevOps seeks to align the output of development shops with the teams charged with putting software into production, thereby assuring continuous releases as businesses need them.

Red Hat Courts Antsy Unix Users with RHEV 3.6 Release

By

The Linux Foundation

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March 15, 2016

With the release of Red Hat Enterprise Virtualization 3.6, Red Hat has set its sites on helping to move mission critical Unix workloads over to Linux machines.

“We have continued to see demand for mission-critical workloads that have previously avoided virtualization, especially those tied to Unix-to-Linux migrations,” wrote Scott Herold, Red Hat principal product manager for RHEV, in an email. “RHEV 3.6 ties these mission-critical workloads directly to Unix-Linux migrations with new storage throughput features.”

The release comes with a number of other new features as well, including add management consoles and tooling capabilities and tighter integration with Red Hat CloudForms, the company’s hybrid cloud management software.