Linux Fu: Superpowers For Mere Mortals

July 26, 2021 by Al Williams 27 Comments

You can hardly mention the sudo command without recalling the hilarious XKCD strip about making sandwiches. It does seem like sudo is the magic power to make a Linux system do what you want. The only problem is that those superpowers are not something to be taken lightly.

If you are surfing the web, for example, you really don’t want to be root, because if someone naughty takes over your computer they could do a lot more harm with your root password. But still, there are times when you want to run certain commands that are normally root-only and don’t want to bother with a password. Luckily, sudo can handle that use case very easily.

Why?

As a simple example, suppose you like to shut your computer down at the end of the day. You run the shutdown command from the terminal but it doesn’t work because you aren’t root. You then have to do it again with sudo and if you haven’t logged in lately, provide your password. Ugh.

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The Linux Kernel 5.14 Audio Update

July 13, 2021 by Jonathan Bennett 39 Comments

You may remember the Pipewire coverage we ran a couple weeks ago, and the TODO item to fix up Firewire device support with Pipewire. It turns out that this is an important feature for kernel hackers, too, because the Alsa changes just got pulled into the 5.14 kernel, and included is the needed Firewire audio work. Shout-out to [Marcan] for pointing out this changeset. Yes, that’s the same as [Hector Martin], the hacker bringing Linux to the M1, who also discovered M1racles. We’ve covered some of his work before.

It turns out that some Firewire audio devices expect timing information in the delivery stream to match the proper playback time for the audio contained in the stream. A naive driver ends up sending packets of sound to the Firewire device that wanted to be played before the packet arrives. No wonder the devices didn’t work correctly. I’m running a 5.14 development kernel, and so far my Focusrite Saffire Pro40 has been running marvelously, where previous kernels quickly turned its audio into a crackling mess.

There is another fix that’s notable for Pipewire users, a reduction in latency for USB audio devices. That one turned out to be not-quite-correct, leading to a hang in the kernel on Torvald’s machine. It’s been reverted until the problem can be corrected, but hopefully this one will land for 5.14 as well. (Edit: The patch was cleaned up, and has been pulled for 5.14. Via Phoronix.) Let us know if you’d like to see more kernel development updates!

Linux Fu: PDF For Penguins

July 6, 2021 by Al Williams 44 Comments

PostScript started out as a programming language for printers. While PostScript printers are still a thing, there are many other ways to send data to a printer. But PostScript also spawned the Portable Document Format or PDF and that has been crazy successful. Hardly a day goes by that you don’t see some kind of PDF document come across your computer screen. Sure, there are other competing formats but they hold a sliver of market share compared to PDF. Viewing PDFs under Linux is no problem. But what about editing them? Turns out, that’s easy, too, if you know how.

GUI Tools

You can use lots of tools to edit PDF files, but the trick is how good the results will look. Anything will work for this: LibreOffice Draw, Inkscape, or even GIMP. If all you want to do is remove something with a white box or make an annotation, these tools are usually great, but for more complicated changes, or pixel-perfect output, they may not be the right tool.

The biggest problem is that most of these tools deal with the PDF as an image or, at least, a collection of objects. For example, columns of text will probably turn into a collection of discrete lines. Changing something that causes a line to wrap will require you to change all the other lines to match. Sometimes text isn’t even text at all, but images. It largely depends on how the creator made the PDF to begin with. Continue reading “Linux Fu: PDF For Penguins” →

Rocky Linux Is Ready For Prime Time!

June 24, 2021 by Jonathan Bennett 23 Comments

For some small percentage of the Hackaday crowd, our world got turned upside down at the end of last year, when Red Hat announced changes to CentOS. That distro is the official repackage of Red Hat Enterprise Linux, providing a free, de-branded version of RHEL. The big problem was that CentOS 8 support has been cut way short, ending at the end of 2021 instead of the expected 2029. This caused no shortage of consternation in the community, and a few people and companies stepped forward to provide their own CentOS alternative, with AlmaLinux and Rocky Linux being the two most promising. AlmaLinux minted their first release in March, but the Rocky project made the decision to take things a bit slower. The wait is over, and the Rocky Linux 8.4 release is ready.

Not only are there ISOs for new installs, there is also a script to convert a CentOS 8 install to Rocky. Now before you run out and convert all your CentOS machines, there are a few caveats. First, the upgrade script is still being tested and fixed as problems are found. The big outstanding issue is that Secure Boot isn’t working yet. The process of spinning up a new Secure Boot shim and getting it properly signed is non-trivial, and takes time. The plan is to do an 8.4 re-release when the shim is ready, so keep an eye out for that, if you need Secure Boot support.

The future looks bright for enterprise Linux, with options such as Rocky Linux, AlmaLinux, and even CentOS Stream. It’s worth noting that Rocky has a newly formed company behind it, CIQ, offering support if you want it. The Rocky crew is planning a launch party online on June 25th, so tune in if that’s your thing. Regardless of which Linux OS you run, it’s good to have Rocky in the game.

A Collection Of Linux Tools On Steroids

June 21, 2021 by Al Williams 75 Comments

Sometimes we do things because “that’s the way we’ve always done them.” Screws, for example, had slotted heads in the 1500s and slotted heads are notoriously bad, but despite Robertson in 1907 and Phillips in the 1930s, it took decades for slotted screw heads to become uncommon and they still lurk in a few areas. Many Linux tools we use every day are direct descendants from Unix tools that have been around for almost half a century. We’ve looked at a few more modern alternatives before, and [ibraheemdev] has a GitHub collection of many such tools that’s worth checking out.

Of course, modern doesn’t always mean better. However, the tools in the list do have great features including things that were uncommon in the old days such as the use of color, text-based graphics, and things like git integration.

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Linux Fu: Databases Are Next-Level File Systems

June 8, 2021 by Al Williams 63 Comments

It is funny how exotic computer technology eventually either fails or becomes commonplace. At one time, having more than one user on a computer at once was high tech, for example. Then there are things that didn’t catch on widely like vector display or content-addressable memory. The use of mass storage — especially disk drives — in computers, though has become very widespread. But at one time it was an exotic technique and wasn’t nearly as simple as it is today.

However, I’m surprised that the filesystem as we know it hasn’t changed much over the years. Sure, compared to, say, the 1960s we have a lot better functionality. And we have lots of improvements surrounding speed, encoding, encryption, compression, and so on. But the fundamental nature of how we store and access files in computer programs is stagnant. But it doesn’t have to be. We know of better ways to organize data, but for some reason, most of us don’t use them in our programs. Turns out, though, it is reasonably simple and I’m going to show you how with a toy application that might be the start of a database for the electronic components in my lab.

You could store a database like this in a comma-delimited file or using something like JSON. But I’m going to use a full-featured SQLite database to avoid having a heavy-weight database server and all the pain that entails. Is it going to replace the database behind the airline reservation system? No. But will it work for most of what you are likely to do? You bet. Continue reading “Linux Fu: Databases Are Next-Level File Systems” →

Spell Checking Your Programming From The Linux Command Line

May 29, 2021 by Al Williams 17 Comments

For most of us who didn’t do well in high school English class, spell checkers are a real game-changer. Sure, you can still swap a “to” and a “too,” but a spell checker will catch a lot of typos. But what about in your source code? You usually don’t spell check source code and even if you did, the rules are funny. After all, “my_proejct” is a perfectly fine variable name, but you probably meant “my_project.” That’s where a program called typos comes in. It aims to be a spell checker for source code that is fast enough and with a low enough false positive rate that you can run it against changed code and reject spelling problems.

Sure, if “my_proejct” is a one-time typo, the compiler or interpreter will probably catch it. But it won’t catch comments and it also won’t catch something you spell wrong consistently. For that you need something like typos.

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