Linux Hacks

528 Articles

A Shell? A Programming Language? Relax! It’s Both!

August 8, 2020 by 55 Comments

Every time we publish a Linux hack that uses a shell script, someone will chime in about how awful it is to program shell scripts. While we like the ubiquity and efficiency, we can’t disagree that the shell is a bit of a hack itself. [Axel Lijencrantz] wants to change your shell to be a full-blow programming language called Crush.

On the face of it, it looks like a shell. Want to see the contents of the current directory? Simple: ls.

The difference is underneath. In Crush, ls is a built-in and it returns data in rows like a database. You can manipulate that database with SQL-like commands: ls | where {type=="directory"}.

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Linux-Fu: Help Messages For Shell Scripts And Here Documents

August 3, 2020 by 20 Comments

Imagine that you want to output multiple lines of text in Bash, or any shell script. Maybe it’s for a help string for a particularly convoluted shell script you’re writing. You could have a separate echo command for each line.  Or you could use the “here document“.

The “here document” construction takes the text between two delimiters and passes it, as if it were piped, to a command.

if [[$# == 0 ]] || [[ "$1" == "-h" ]]; then
cat << EOF
This is my help message. There are many like it but this one is mine.
My help message is my best friend.
EOF

All of the text, as written, with line breaks and spaces and all, get passed to cat and your helpful formatted message is printed to the user.

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Linux Fu: Keep In Sync

July 23, 2020 by 28 Comments

Once upon a time, computers were very expensive and you were lucky to have shared access to one computer. While that might seem to be a problem, it did have one big advantage: all of your files were on that computer.

Today, we all probably have at least a desktop and one laptop. Your phone is probably a pretty good computer by most standards. You might have multiple computers and a smattering of tablets. So what do you do to keep your files accessible everywhere? Why not run your own peer-to-peer synchronization service? Your files are always under your control and encrypted in motion. There’s no central point of failure. You can do it with one very slick piece of Open Source software called syncthing. It runs on Windows, Linux, Mac, BSD, and Solaris. There are also Android clients. We haven’t tested it, but one caveat is that the unofficial iOS support sounds a little spotty.

The joke about the cloud — that it’s just other people’s servers — is on point here. Some people don’t like their files sitting on a third-party server. Even if your files are encrypted or you don’t care, you still have the problem of what happens if you can’t reach the server — may be on an airplane with no WiFi — or the server goes down. Sure, Google and Microsoft don’t go dark very often, but they can and do. Even if you build your own cloud, it runs on your servers. Syncthing is serverless: it simply makes sure that all files are up-to-date on all your end devices. Continue reading “Linux Fu: Keep In Sync” →

Synthesizer Gets An External Touch Screen

July 8, 2020 by 3 Comments

Like other owners of the high-end Yamaha MODX, [sn00zerman] wasn’t happy with the synthesizer’s integrated touch screen. It’s a bit small, and not at a very good angle for viewing. So he made it his mission to find some way of adding a larger external touch screen without making any permanent modifications to the expensive instrument.

This might seem like a tall order, but he wasn’t starting from zero. It was already known that you could plug an external display into it if you used a USB to DVI/HDMI adapter; but without the touch overlay it wasn’t a particularly useful trick. He pondered adding an external connector for the device’s built-in touch screen overlay, but that broke his no modifications rule. Considering how much one of these things cost, we can’t blame him for not wanting to put a hole in the side.

Sometimes you just have to dig out the right parts.

So he started to look for a software solution to get him the rest of the way. Luckily the MODX runs Linux, and Yamaha has made good on their GPL responsibilities and released the source code for anyone who’s interested. While poking around, he figured out that the device uses tslib to talk to the touch screen, which [sn00zerman] had worked with on previous projects. He realized that the solution might be as simple as finding a USB touch screen controller that’s compatible with the version of tslib running on the MODX.

In the end, a trip through his parts bin uncovered a stand-alone touch screen controller that he knew from experience would work with the library. Sure enough, when plugged into the MODX, the OS accepted it as an input device. With the addition of a USB hub, he was able to combine this with an existing display and finally have a more comfortable user-interface for his synthesizer.

Now all he’s got to do is plug in a USB floppy drive, and he’ll have the ultimate Yamaha Beat Laboratory.

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Linux-Fu: Parallel Universe

June 29, 2020 by 38 Comments

At some point, you simply run out of processing power. Admittedly, that point keeps getting further and further away, but you can still get there. If you run out of CPU time, the answer might be to add more CPUs. However, sometimes there are other bottlenecks like memory or disk space. However, it is also likely that you have access to multiple computers. Who doesn’t have a few Raspberry Pis sitting around their network? Or maybe a server in the basement? Or even some remote servers “in the cloud.” GNU Parallel is a tool that lets you spread work across multiple tasks either locally to remote machines. In some ways, it is simple, since it looks sort of like xargs but with parallel execution. On the other hand, it has myriad options and configurations that can make it a little daunting to use. Continue reading “Linux-Fu: Parallel Universe” →

Linux-Fu: Automation For Chrome And The Desktop By Matching Screenshots

June 15, 2020 by 11 Comments

I will be the first to admit it. This is almost not — at least not specifically — a Linux article. The subject? An automation tool for Chrome or Firefox. But before you hit the back button, hear me out. Sure, this Chrome plugin started out as a tool to automatically test web pages and automate repetitive tasks in the browser. However, it can extend that power to all programs on your computer. So, in theory, you can use it to graphically build macros that can interact with desktop applications in surprisingly sophisticated ways. In theory, anyway; there are a few problems.

The program has a few different names. Most documentation says UI Vision RPA, although there are some references to Kantu, which appears to be an older name. RPA is an acronym for Robotic Process Automation, which is an industry buzz word.

Let’s take it for a spin and see what it’s all about.

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Python Is All You’ll Ever Need In This Linux Distro

June 1, 2020 by 32 Comments

Choosing the perfect Linux distribution that satisfies your personal needs and likings can be an impossible task, and oftentimes requires a hint of Stockholm syndrome as compromise. In extreme cases, you might end up just rolling your own distro. But while frustration is always a great incentive for change, for [Josh Moore] it was rather curiosity and playful interest that led him to create snakeware, a Linux distribution where the entire user space not only runs on Python, but is Python.

Imagine you would boot your Linux system, and instead of the shell of your choice, you would be greeted by an interactive Python interpreter, and everything you do on the system will be within the realms of that interpreter — that’s the gist of snakeware. Now, this might sound rather limiting at first, but keep in mind we’re talking about Python here, a language known for its versatility, with an abundance of packages that get things done quick and easy, which is exactly what [Josh] is aiming for. To get an idea of that, snakeware also includes snakewm, a graphical user interface written with pygame that bundles a couple of simple applications as demonstration, including a terminal to execute Python one-liners.

Note that this is merely a proof of concept at this stage, but [Josh] is inviting everyone to contribute and extend his creation. If you want to give it a go without building the entire system, the GitHub repository has a prebuilt image to run in QEMU, and the window manager will run as regular Python application on your normal system, too. To get just a quick glimpse of it, check the demo video after the break.

Sure, die-hard Linux enthusiasts will hardly accept a distribution without their favorite shell and preferable language, but hey, at least it gets by without systemd. And while snakeware probably won’t compete with more established distributions in the near future, it’s certainly an interesting concept that embraces thinking outside the box and trying something different. It would definitely fit well on a business card.

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