You may forget the complex and lengthy Linux commands after certain period of time unless you’re a heavy command line user. Sure, there are a few ways to recall the forgotten commands. You could simply save the frequently used commands and use them on demand. Also, you can bookmark the important commands in your Terminal and use whenever you want. And, of course there is already a built-in “history” command available to help you to remember the commands. Another easiest way to remember such long commands is to simply create an alias (shortcut) to them. Not just long commands, you can create alias to any frequently used Linux commands for easier repeated invocation. By this approach, you don’t need to memorize those commands anymore. In this guide, we are going to learn about alias and unalias commands with examples in Linux.
The alias command
The alias command is used to run any command or set of commands (inclusive of many options, arguments) with a user-defined string. The string could be a simple name or abbreviations for the commands regardless of how complex the original commands are. You can use the aliases as the way you use the normal Linux commands. The alias command comes preinstalled in shells, including BASH, Csh, Ksh and Zsh etc.
At some point in your career as a Linux administrator, you’re going to use Secure Shell (SSH) to remote into a Linux server or desktop. Chances are, you already have. In some instances, you’ll be SSH’ing into multiple Linux servers at once. In fact, Secure Shell might well be one of the most-used tools in your Linux toolbox. Because of this, you’ll want to make the experience as efficient as possible. For many admins, nothing is as efficient as the command line. However, there are users out there who do prefer a GUI tool, especially when working from a desktop machine to remote into and work on a server.
If you happen to prefer a good GUI tool, you’ll be happy to know there are a couple of outstanding graphical tools for SSH on Linux. Couple that with a unique terminal window that allows you to remote into multiple machines from the same window, and you have everything you need to work efficiently. Let’s take a look at these three tools and find out if one (or more) of them is perfectly apt to meet your needs.
I’ll be demonstrating these tools on Elementary OS, but they are all available for most major distributions.
PuTTY
Anyone that’s been around long enough knows about PuTTY. In fact, PuTTY is the de facto standard tool for connecting, via SSH, to Linux servers from the Windows environment. But PuTTY isn’t just for Windows. In fact, from withing the standard repositories, PuTTY can also be installed on Linux. PuTTY’s feature list includes:
Saved sessions.
Connect via IP address or hostname.
Define alternative SSH port.
Connection type definition.
Logging.
Options for keyboard, bell, appearance, connection, and more.
Local and remote tunnel configuration
Proxy support
X11 tunneling support
The PuTTY GUI is mostly a way to save SSH sessions, so it’s easier to manage all of those various Linux servers and desktops you need to constantly remote into and out of. Once you’ve connected, from PuTTY to the Linux server, you will have a terminal window in which to work. At this point, you may be asking yourself, why not just work from the terminal window? For some, the convenience of saving sessions does make PuTTY worth using.
Installing PuTTY on Linux is simple. For example, you could issue the command on a Debian-based distribution:
sudo apt-get install -y putty
Once installed, you can either run the PuTTY GUI from your desktop menu or issue the command putty. In the PuTTY Configuration window (Figure 1), type the hostname or IP address in the HostName (or IP address) section, configure the port (if not the default 22), select SSH from the connection type, and click Open.
Figure 1: The PuTTY Connection Configuration Window.
Once the connection is made, you’ll then be prompted for the user credentials on the remote server (Figure 2).
Figure 2: Logging into a remote server with PuTTY.
To save a session (so you don’t have to always type the remote server information), fill out the IP address (or hostname), configure the port and connection type, and then (before you click Open), type a name for the connection in the top text area of the Saved Sessions section, and click Save. This will then save the configuration for the session. To then connect to a saved session, select it from the saved sessions window, click Load, and then click Open. You should then be prompted for the remote credentials on the remote server.
EasySSH
Although EasySSH doesn’t offer the amount of configuration options found in PuTTY, it’s (as the name implies) incredibly easy to use. One of the best features of EasySSH is that it offers a tabbed interface, so you can have multiple SSH connections open and quickly switch between them. Other EasySSH features include:
Groups (so you can group tabs for an even more efficient experience).
Username/password save.
Appearance options.
Local and remote tunnel support.
Install EasySSH on a Linux desktop is simple, as the app can be installed via flatpak (which does mean you must have Flatpak installed on your system). Once flatpak is installed, add EasySSH with the commands:
The EasySSH app will open, where you can click the + button in the upper left corner. In the resulting window (Figure 3), configure your SSH connection as required.
Figure 3: Adding a connection in EasySSH is simple.
Once you’ve added the connection, it will appear in the left navigation of the main window (Figure 4).
Figure 4: The EasySSH main window.
To connect to a remote server in EasySSH, select it from the left navigation and then click the Connect button (Figure 5).
Figure 5: Connecting to a remote server with EasySSH.
The one caveat with EasySSH is that you must save the username and password in the connection configuration (otherwise the connection will fail). This means anyone with access to the desktop running EasySSH can remote into your servers without knowing the passwords. Because of this, you must always remember to lock your desktop screen any time you are away (and make sure to use a strong password). The last thing you want is to have a server vulnerable to unwanted logins.
Terminator
Terminator is not actually an SSH GUI. Instead, Terminator functions as a single window that allows you to run multiple terminals (and even groups of terminals) at once. Effectively you can open Terminator, split the window vertical and horizontally (until you have all the terminals you want), and then connect to all of your remote Linux servers by way of the standard SSH command (Figure 6).
Figure 6: Terminator split into three different windows, each connecting to a different Linux server.
To install Terminator, issue a command like:
sudo apt-get install -y terminator
Once installed, open the tool either from your desktop menu or from the command terminator. With the window opened, you can right-click inside Terminator and select either Split Horizontally or Split Vertically. Continue splitting the terminal until you have exactly the number of terminals you need, and then start remoting into those servers. The caveat to using Terminator is that it is not a standard SSH GUI tool, in that it won’t save your sessions or give you quick access to those servers. In other words, you will always have to manually log into your remote Linux servers. However, being able to see your remote Secure Shell sessions side by side does make administering multiple remote machines quite a bit easier.
Few (But Worthwhile) Options
There aren’t a lot of SSH GUI tools available for Linux. Why? Because most administrators prefer to simply open a terminal window and use the standard command-line tools to remotely access their servers. However, if you have a need for a GUI tool, you have two solid options and one terminal that makes logging into multiple machines slightly easier. Although there are only a few options for those looking for an SSH GUI tool, those that are available are certainly worth your time. Give one of these a try and see for yourself.
Learn more about Linux through the free “Introduction to Linux” course from The Linux Foundation and edX.
“When it comes to Kubernetes, and containers and microservices in general, there’s a big gap between what it takes to run in the ‘lab’ and what it takes to run in full production,” says Ranga Rajagopalan, cofounder and CTO of Avi Networks. “It’s the difference between simply running, and running securely and reliably.”
There’s an important starting point in Rajagopalan’s comment: This isn’t just a Kubernetes issue, per se, but rather more widely applicable to containers and microservices. It is relatively “easy” to deploy a container; operating and scaling containers (and containerized microservices) in production is what introduces complexity.
What makes it a “Developer Edition” besides the top-of-the-line hardware is its software configuration. Canonical, Ubuntu‘s parent company, and Dell worked together to certify Ubuntu 18.04 LTS on the XPS 13 9370. This worked flawlessly on my review system.
U.S. consumers are expected to drop a bundle this Black Friday on smart speakers and home hubs. A Nov. 15 Canalys report estimates that shipments of voice-assisted speakers grew 137 percent in Q3 2018 year-to-year and are on the way to 75 million-unit sales in 2018. At the recent Embedded Linux Conference and Open IoT Summit in Edinburgh, embedded Linux developer and Raspberry Pi HAT creator Leon Anavi of the Konsulko Group reported on the latest smart speaker trends.
As Anavi noted in his “Comparison of Voice Assistant SDKs for Embedded Linux Devices” talk, conversing with computers became a staple of science fiction over half a century ago. Voice technology is interesting “because it combines AI, big data, IoT, and application development,” said Anavi.
In Q3 2017, Amazon and Google owned the industry with 74.7 percent and 24.6 percent, respectively, said Canalys. A year later, the percentages were down to 31.9 and 29.8. China-based Alibaba and Xiaomi almost equally split another 21.8 percent share, followed by 17.4 percent for “others,” which mostly use Amazon Alexis, and increasingly, Google Assistant.
Despite the success of the mostly Linux-driven smart speaker market, Linux application developers have not jumped into voice app development in the numbers one might expect. In part, this is due to reservations about Google and Amazon privacy safeguards, as well as the proprietary nature of the hardware and cloud software.
“Privacy is a concern with smart speakers,” said Anavi. “You can’t fully trust a corporation if the product is not open source.”
Anavi summarized the Google and Amazon SDKs but spent more time on the fully open source Mycroft Mark. Although Anavi clearly prefers Mycroft, he encouraged developers to investigate all the platforms. “There is a huge demand in the market for these devices and a lot of opportunity for IoT integration, from writing new skills to integrating voice assistants in consumer electronics devices,” said Anavi.
Alexa/Echo
Amazon’s Alexa debuted in the Echo smart speaker four years ago. Amazon has since expanded to the Echo branded Dot, Spot, Tap, and Plus speakers, as well as the Echo Show and new Echo Show 2 display hubs.
The market leading Echo devices run on Amazon’s Linux- and Android-based Fire OS. The original Echo and Dot ran on the Cortex-A8-based TI DM3725 SoC while more recent devices have moved to an Armv8 MediaTek MT8163V SoC with 256MB RAM and 4GB flash.
Thanks to Amazon’s wise decision to release an Apache 2.0 licensed Alexa Voice Services (AVS) SDK, Alexa also runs on most third-party hubs. The SDK includes an Alexa Skills Kit for creating custom Skills. The cloud platform required to make Alexa devices work is not open source, however, and commercial vendors must sign an agreement and undergo a certification process.
Alexa runs on a variety of hardware including the Raspberry Pi, as well as smart devices ranging from the Ecobee4 Smart Thermostat to the LG Hub Robot. Microsoft recently began selling Echo devices, and earlier this year partnered with Amazon to integrate Alexa with its own Cortana voice agent in devices. This week, Microsoft announced that users can voice-activate Skype calls via Alexa on Echo devices.
Google Assistant/Home
The Google Assistant voice agent debuted on the Google Home smart speaker in 2016. It has since expanded to the Echo Dot-like Home Mini, which like the Home runs on a 1.2GHz dual-core Cortex-A7 Marvell Armada 1500 Mini Plus with 512MB RAM and 4GB flash. This year’s Home Max offered improved speakers and advanced to a 1.5GHz, quad-core Cortex-A53 processor. More recently, Google launched the touchscreen enabled Google Home Hub.
The Google Home devices run on a version of the Linux-based Google Cast OS. Like Alexa, the Python driven Google Assistant SDK lets you add the voice agent to third-party devices. However, it’s still in preview stage and lacks an open source license. Developers can create applications with Google Actions.
Last year, Google launched a version of its Google Assistant SDK for the Raspberry Pi 3 and began selling an AIY Voice Kit that runs on the Pi. There’s also a kit that runs on the Orange Pi, said Anavi.
This year, Google has aggressively courted hardware partners to produce home hub devices that combine Assistant with Google’s proprietary Android Things. The devices run on a variety of Arm-based SoCs led by the Qualcomm SD212 Home Hub Platform.
The SDK expansion has resulted in a variety of third-party devices running Assistant, including the Lenovo Smart Display and the just released LG XBOOM AI ThinQ WK9 touchscreen hubs. Sales of Google Home devices outpaced Echo earlier this year, although Amazon regained the lead in Q3, says Canalys.
Like Alexa, but unlike Mycroft, Google Assistant offers multilingual support. The latest version supports follow-up questions without having to repeat the activation word, and there’s a voice match feature that can recognize up to six users. A new Google Duplex feature accomplishes real-world tasks through natural phone conversations.
Mycroft/Mark
Anavi’s favorite smart speaker is the Linux-driven, open source (Apache 2.0 and CERN) Mycroft. The Raspberry Pi based Mycroft Mark 1 speaker was certified by the Open Source Hardware Association (OSHA).
The Mycroft Mark II launched on Kickstarter in January and has received $450,000 in funding. This Xilinx Zynq UltraScale+ MPSoC driven home hub integrates Aaware’s far-field Sound Capture technology. A Nov. 15 update post revealed that the Mark II will miss its December ship date.
Kansas City-based Mycroft has raised $2.5 million from institutional investors and is now seeking funding on StartEngine. Mycroft sees itself as a software company and is encouraging other companies to build the Mycroft Core platform and Mycroft AI voice agent into products. The company offers an enterprise server license to corporate customers for $1,500 a month, and there’s a free, Raspbian based Picroft application for the Raspberry Pi. A Picroft hardware kit is under consideration.
Mycroft promises that user data will never be saved without an opt-in (to improve machine learning algorithms), and that it will never be used for marketing purposes. Like Alexa and Assistant, however, it’s not available offline without a cloud service, a feature that would better ensure privacy. Anavi says the company is working on an offline option.
The Mycroft AI agent is enabled via a Python based Mycroft Pulse SDK, and a Mycroft Skills Manager is available for Skills development. Like Alexa and Assistant, Mycroft supports custom wake words. The new version uses its homegrown Precise wake-word listener technology in place of the earlier PocketSphinx. There’s also an optional device and account management stack called Mycroft Home.
For text-to-speech (TTS), Mycroft defaults to the open source Mimic, which is co-developed with VocaliD. It also supports eSpeak, MaryTTS, Google TTS, and FATTS.
Mycroft lacks its own speech to-text (STT) engine, which Anavi calls “the biggest challenge for an open source voice assistant.” Instead, it defaults to Google STT and supports IBM Watson STT and wit.ai.
Mycroft is collaborating with Mozilla on its open source DeepSpeech STT, an open source TensorFlow implementation of Baidu’s DeepSpeech platform. Baidu trails Alibaba and Xiaomi in the Chinese voice assistant market but is one of the fastest growing voice AI companies. Just as Alibaba uses its homegrown, Alexa-like AliGenie agent on its Tmall Genie speaker, Baidu loads its speakers with its DeepSpeech-driven DuerOS voice platform. Xiaomi has used Alexa and Cortana.
Mycroft is the most mature of several alternative voice AI projects that promise improved privacy safeguards. A recent VentureBeat article reported on emerging privacy-oriented technologies including Snips and SoundHound.
Anavi concluded with some demo videos showing off his soothing, Bulgarian AI whisperer vocal style. “I try to be polite with these things,” said Anavi. “Someday they may rule the world and I want to survive.”
Cron is nice and all, but don’t forget about its cousin at.
…even though I’ve been using Linux for 20 years, I still learn about new (to me) command-line tools all the time. In this “Back to Basics” article series, I plan to cover some of the command-line tools that those new to Linux may never have used before. For those of you who are more advanced, I’ll spread out this series, so you can expect future articles to be more technical. In this article, I describe how to use the at utility to schedule jobs to run at a later date.
at vs. Cron
at is one of those commands that isn’t discussed very much. When people talk about scheduling commands, typically cron gets the most coverage. Cron allows you to schedule commands to be run on a periodic basis. With cron, you can run a command as frequently as every minute or as seldom as once a day, week, month or even year. You also can define more sophisticated rules, so commands run, for example, every five minutes, every weekday, every other hour and many other combinations. System administrators sometimes will use cron to schedule a local script to collect metrics every minute or to schedule backups.
A while back, we released a demo of the nabla containers runtime, runnc (v0.1). Most recently, we have improved our runtime in several aspects such as better start-up times and memory density. In addition to that (and also the focus of this blogpost), we have implemented Nabla support for kubernetes! In this blog post, we will show a simple local setup of kubernetes using the nabla containers runtime, runnc (v0.2), through containerd via the untrusted workload CRI plugin and pod annotation.
There will be several steps to achieve this on a local machine:
The practice of building and maintaining open source software works because people from all over the world, of all abilities and backgrounds, form communities to support the projects they care about. It’s not difficult to support the open source projects you use every day, and the efforts you make will have tangible effects on the quality of that software.
Most open source projects don’t have a dedicated staff to support them. Instead, developers and users from around the world work on them, often in their spare time. For many programmers, though, the thought of contributing to open source projects seems too difficult and time-consuming. They think that you have to be a programming genius blessed with unlimited free time to make a meaningful contribution.
That’s simply not true. Successful open source projects thrive on a wide variety of contributions from people with all levels of coding skills and commitment.
A number of home automation platforms support Python as an extension, but if you’re a real Python fiend, you’ll probably want Home Assistant, which places the programming language front and center. Paulus Schoutsen created Home Assistant in 2013 “as a simple script to turn on the lights when the sun was setting,” as he told attendees of his 2016Embedded Linux Conference and Open IoT conference presentation. (You can watch the complete video below.)
Schoutsen, who works as a senior software engineer for AppFolio in San Diego, has attracted 20 active contributors to the project. Home Assistant is now fairly mature, with updates every two weeks and support for more than 240 different smart devices and services. The open source (MIT license) software runs on anything that can run Python 3, from desktop PCs to a Raspberry Pi, and counts thousands of users around the world.
Like most automation systems, Home Assistant offers mobile and desktop browser clients to control smart home devices from afar. It differs from most commercial offerings, however, in that it has no hub appliance, which means there are no built-in radios. You can add the precisely those radios you want, however, using USB sticks. There’s also no cloud component, but Schoutsen argues that any functionality you might sacrifice because of this is more than matched by better security, privacy, and resiliency.
“There is no dependency on a cloud provider,” said Schoutsen. “Even when the Internet goes down, the home doesn’t shut down, and your very private data stays in your home.”
Schoutsen did not offer much of a promo in his presentation, but quickly set to work explaining how the platform works. Since Home Assistant is not radically different from other IoT frameworks — one reason why it interfaces easily with platforms ranging from Nest to Arduino to Kodi — the presentation is a useful introduction to IoT concepts.
To get a better sense of Home Assistant’s strengths, I recently asked Schoutsen for his elevator pitch. He highlighted the free, open source nature of the software, as well as the privacy and security of a local solution. He also noted the ease of setup and discovery, and the strength of the underlying Python language.
Easy Extensions
“Python makes it very easy to extend the system,” Schoutsen told me. “As a dynamic language it allows a flexibility that Java developers can only dream off. It is very easy to test out and prototype new pieces on an existing installation without breaking things permanently. With the recent introduction of MicroPython, which runs on embedded systems as Arduino and ESP8266, we can offer a single language for all levels of IoT: from sensors to automation to integration with third-party services.”
In Schoutsen’s ELC 2016 presentation, he described how Home Assistant is an event-driven program that incorporates a state machine that keeps track of “entities” — all the selected devices and people you want to track. Each entity has an identifier, a state condition, and attributes. The latter describes more about the state, such as the color and intensity of the light on a Philips Hue smart bulb.
To integrate a Philips Hue into the system, for example, you would need to use a light “component,” which is aware of the bulb and how to read its state (off or on). Home Assistant offers components for every supported device or service, as well as easy access to component groups such as lights, thermostats, switches, and garage doors. Setup is eased with a network discovery component that scans the network and, if you have a supported device, sets it up automatically.
The software is further equipped with a service registry, which provides services over the event bus. “We can register the turn-on command for a light, and have it send an email or SMS,” said Schoutsen. “A timer can send a time change event every second, and a component can ask to be notified at a particular time, or in intervals. Based on time change events, it will trigger the callback of the components.”
Each component writes its state to the state machine, emitting a state change event to the event bus. “The light component would register its turn on service inside the service registry so that anyone could fire an event to the event bus to turn on the light,” said Schoutsen.
You can easily integrate a light component with a motion detector component using an automation component. This would listen to the motion detector events, and fire a “turn light on” event to the event bus, which in turn would be forwarded to the service registry. The registry would then check to see that the light component can handle the event. “Automation components can listen for events, observe certain attribute states or triggers, and act on them,” explained Schoutsen.
Another component type handles presence detection. “The platform can check the router to see which phones are connected in order to see who is home,” said Schoutsen. “Other components are responsible for recording event and state history, or for entity organization — grouping multiple entities and summarizing their state.” Components are available for integrating third party services, such as MQTT or IFTTT, and other components export data to external databases and analysis tools.
Schoutsen went on to explain concepts such as a “platform” layer that sits above the entity components. Each platform integrates an “abstract base class,” which “acts as the glue between the real device and the one represented in Home Assistant,” said Schoutsen. Later, he ran through a code example for a basic switch and explored the use of trigger zones for geofencing.
As Schoutsen says, Home Assistant is “gaining a lot of traction.” Check out the complete video to see what happens when Python meets IoT.
At the core of every technology on GitHub is a programming language. In this year’s Octoverse report, we published a brief analysis of which ones were best represented or trending on GitHub. In this post, we’ll take a deeper dive into why—and where—top programming languages are popular.
There are dozens of ways to measure the popularity of a programming language. In our report, we used the number of unique contributors to public and private repositories tagged with the appropriate primary language. We also used the number of repositories created and tagged with the appropriate primary language.
Top programming languages by repositories created, 2008-2018
