linux

652 Articles

Linux Fu: WSL Tricks Blur The Windows/Linux Line

December 23, 2019 by 51 Comments

We have to admit, we have an odd fascination with WSL — the Windows subsystem for Linux. On the one hand, it gives us more options on Windows 10 for running the software we love. On the other hand, we wonder why we aren’t just running Linux. Sometimes it is because our cool laptop doesn’t work well on Linux. Other times we are using someone else’s computer that we aren’t allowed to reload or dual boot. Still, as long as we have to use Windows, we are glad to have WSL. A recent blog post by [Hanselman] shows some very cool tricks for using WSL that make it even better.

Exploring WSL

Did you know you can use WSL to run Linux commands in a Windows command shell? For example, you have a long directory and you want to run grep:

dir c:\archive\* | wsl grep -i hackaday

Of course, from bash you could access the same directory:

ls /mnt/c/archive | grep -i hackaday

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Linux Fu: Stupid SSH Tricks

December 17, 2019 by 52 Comments

If you connect to remote computers over the Internet, it is a pretty good chance you use some form of SSH or secure shell. On Linux or Unix you’ll use the ssh command. Same goes for Linux-like environments on Windows like Cygwin or WSL. For native Windows, you might be using Putty. In its simplest form, ssh is just a terminal program that talks to a server using an encrypted connection. We think it is very hard to eavesdrop on anyone communicating with a remote computer via ssh.

There are several tricks for using ssh — some are pretty straightforward and some are things you might not think of as being in the domain of a terminal program. You probably know that ssh can copy files securely, and there are easy and hard ways to set up logging in with no password.

However, you can also mount a remote filesystem via ssh (actually, there are several ways to do that). You can use ssh to securely browse the web in your favorite browser, or even use it to tunnel specific traffic by port or even use it as a makeshift VPN. In fact, there’s so much ground to cover that this won’t be the last Linux Fu to talk about ssh. But enough setup, let’s get to the tricks.

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Nintendo Switch Doubles As Network Switch

December 16, 2019 by 12 Comments

Coming straight to you from the “Department of Redundant Redundancies” comes this clever hack that turns a Switch into a switch. More specifically, a network switch. Not even a half bad one either, judging by the speed tests [Cynthia Revström] performed after setting it all up. We wouldn’t advise you dump your existing network gear in favor of a repurposed game system, but perhaps in a pinch…

Despite what you might be thinking, there’s no hardware modifications at work here. This is a fully functional Nintendo Switch that’s just had two USB to Ethernet adapters plugged into it. The secret ingredient is the addition of some Penguin Power, up and running on Nintendo’s latest and greatest thanks to a project called switchroot.

With Linux running on the system, all [Cynthia] had to do was make sure that the USB to Ethernet adapters were supported, and fiddle around with the brctl and ip commands to configure a bridge between the interfaces to get the packets moving. Putting the Switch between the main network and a test computer showed it had a throughput of just over 90 Mbps, which is about all that could be expected from the USB-connected network interfaces.

From here it wouldn’t have taken much more effort to get the system working as a wireless router and providing services like DHCP and NAT to clients. But since Nintendo didn’t see fit to call it the Router, that would’ve offered minimal meme value. There’s always next generation.

Seeing the Nintendo Switch do a surprisingly good job running as an Ethernet switch is even more surprising given the fact that it struggles to function with accessories that are actually intended for it. Though to be fair, the migration to USB-C has been a little rockier than most of us would have hoped.

Line Printer Does Its Best Teletype Impression

December 3, 2019 by 22 Comments

Back in the early days of computing, user terminals utilized line printers for output. Naturally this took an incredible amount of paper, but it came with the advantage of creating a hard copy of everything you did. Plus it was easy to annotate the terminal output with nothing more exotic than a ballpoint pen. But once CRT displays became more common, these paper terminals (also known as teleprinters, or teletypes) quickly fell out of style.

A fan of nostalgic hacks, [Drew DeVault] recently tried to recreate the old-school teletype experience with (somewhat) more modern hardware. He picked up an Epson LX-350 line printer, and with a relatively small amount of custom code, he was able to create a fairly close approximation of what it would have been like to use one of these terminals. He’s published all the source code, so if you’ve got an old line printer and a Linux box, you too can learn what it was like to measure your work day in reams of paper.

This is made possible by the fact that the modern Linux virtual terminal is simply a userspace emulation of those physical terminals of yore. [Drew] just need to write some code that would essentially spawn a shell on the Linux USB line printer device, plus sprinkle in some quality of life improvements such as using Epson’s proprietary ANSI escape sequences to feed the paper out far enough so the user can see what it says before pulling it back in to write the next interactive line.

Of course, the experience isn’t perfect as the printer naturally doesn’t have a keyboard attached to it. If you’re looking for something a bit more authentic, you could always convert an old electric typewriter into a modern-ish teletype.

Tales From The Sysadmin: Dumped Into The Grub Command Line

November 25, 2019 by 53 Comments

Today I have a tale of mystery, of horror, and of hope. The allure of a newer kernel and packages was too much to resist, so I found myself upgrading to Fedora 30. All the packages had downloaded, all that was left was to let DNF reboot the machine and install all the new packages. I started the process and meandered off to find a cup of coffee: black, and darker than the stain this line of work leaves on the soul. After enough time had elapsed, I returned, expecting the warming light of a newly upgraded desktop. Instead, all that greeted me was the harsh darkness of a grub command line. Something was amiss, and it was bad.

(An aside to the reader, I had this experience on two different machines, stemming from two different root problems. One was a wayward setting, and the other an unusual permissions problem.)

How does the fledgling Linux sysadmin recover from such a problem? The grub command line is an inscrutable mystery to the uninitiated, but once you understand the basics, it’s not terribly difficult to boot your system and try to restore the normal boot process. This depends on what has broken, of course. If the disk containing your root partition has crashed, then sorry, this article won’t help.

In order to get a system booting, what exactly needs to happen? How does booting Linux work, even? Two components need to be loaded into memory: the kernel, and the initramfs. Once these two elements are loaded into memory, grub performs a jump into the kernel code, which takes over and finishes the machine’s boot. There is one more important detail that we care about — the kernel needs to know where to find the root partition. This is typically part of the kernel parameters, specified on the kernel boot line.

When working with an unfamiliar shell, the help command is a good starting point. grub runs in a very limited environment, and running the help command scrolls most of the text off the screen. There is an environment variable that helps out here, enabling output paging:set pager=1.
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Will The Real UNIX Please Stand Up?

November 5, 2019 by 86 Comments

Ken Thompson and Dennis Ritchie at a PDP-11. Peter Hamer [CC BY-SA 2.0]
Ken Thompson and Dennis Ritchie at a PDP-11. Peter Hamer [CC BY-SA 2.0]
Last week the computing world celebrated an important anniversary: the UNIX operating system turned 50 years old. What was originally developed in 1969 as a lighter weight timesharing system for a DEC minicomputer at Bell Labs has exerted a huge influence over every place that we encounter computing, from our personal and embedded devices to the unseen servers in the cloud. But in a story that has seen countless twists and turns over those five decades just what is UNIX these days?

The official answer to that question is simple. UNIX® is any operating system descended from that original Bell Labs software developed by Thompson, Ritchie et al in 1969 and bearing a licence from Bell Labs or its successor organisations in ownership of the UNIX® name. Thus, for example, HP-UX as shipped on Hewlett Packard’s enterprise machinery is one of several commercially available UNIXes, while the Ubuntu Linux distribution on which this is being written is not.

When You Could Write Off In The Mail For UNIX On A Tape

The real answer is considerably less clear, and depends upon how much you view UNIX as an ecosystem and how much instead depends upon heritage or specification compliance, and even the user experience. Names such as GNU, Linux, BSD, and MINIX enter the fray, and you could be forgiven for asking: would the real UNIX please stand up?

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Linux’s Marketing Problem

October 31, 2019 by 265 Comments

The cult classic movie Office Space is a scathing critique of life for software engineers in a cubicle farm, and it did get a lot of things right even if it didn’t always mean to. One of those is the character of Tom Smykowski whose job is to “deal with the customers so the engineers don’t have to”. The movie treats Tom and his job as a punchline in a way, but his role is actually very important for most real businesses that rely on engineers or programmers for their core products.

Engineers can have difficulty relating to customers, and often don’t have the time (or even willingness) to handle the logistics of interacting with them in the first place. Customers may get frustrated understanding engineers or communicating their ideas clearly to them. A person like Tom Smykowski is often necessary to bridge the gap and smooth out the rough edges on both sides, but in the Linux world there are very few Toms to rely on. The customers, or users, have to deal directly with the engineers in many situations, and it’s not working out very well for either group. Linux has a marketing problem, and it needs a marketing solution if it ever wants to increase its market share in the PC realm. Continue reading “Linux’s Marketing Problem” →