A serious security flaw in macOS High Sierra has been exposed that allows anyone to gain full access to affected Macs without knowing the computer’s administrative password.

The bug appears to let someone log into the admin account on a Mac by simply typing “root” as the username while leaving the password field blank. Attackers could potentially exploit the bug to access locked Macs and gain access to personal information.

By default, any screenshots you take on your Mac, iPad or iPhone get saved as PNG files. That’s great, because PNG files are pixel-perfect, and they support transparency (for those neat floating-window shadows).

But they’re not JPEGs, which means they’re not universally supported. Luckily, you can easily make JPEG screenshots the default, at least on the Mac.

Have you ever wanted to try out a different operating system on your Mac? Ever since Apple started using Intel chips in their computers, it’s been super simple to run Windows and even popular Linux distributions via Boot Camp, virtual environments like Parallels and VMWare Fusion, and the like.

The problem is that you need to use up precious system resources to run these things on your Mac. Even virtual machines take up disk space, as does running Boot Camp and partitioning your main Hard drive. What if you just want to test something out on your Mac before fully committing?

Turns out it’s fairly easy to run Linux on your Mac without using up any bit of your hard drive. Using a flash drive and some Terminal commands, you can check out a distribution like Ubuntu running right on your Mac without having to sacrifice a thing. Here’s how.

If you’re like me, you’re playing Bethesda’s post-apocalyptic RPG Fallout 4 a lot lately. And that probably means you’ve stumbled across a lot of retro CRT monitors that have quasi-Unix systems running on them.

OS X? It’s also a quasi-Unix system. It runs off of a Unix base, which is accessible through the Terminal app.

And if you want Terminal to look like Fallout 4? Just download this app.

Whether you’re a Mac novice or a seasoned veteran, there are a ton of tips and ticks out there for mastering OS X Yosemite. In Part 2 of our Yosemite tip series, we gather more of the very best.

There are times when you just need to clear off the icons on your Desktop, like when you’re giving an important presentation at work. No one wants to see all the images you’ve saved from the internet, right?

I used to solve this problem with a Sort Me folder on the Desktop, just select all in a Finder window focused on the Desktop, and drag it all to the Sort Me folder.

There’s an even faster and easier way to hide all the icons on your Desktop, though, using the Terminal.

If you’ve spent enough time messing around in Terminal, you’ll know one thing for sure: re-typing the stuff you’ve laboriously typed in with only minor differences is tedious. And it happens more often than we’d like.

The Terminal does, however, keep a history of all the commands you’ve typed into it. To see this in action, you can cycle through the last few commands you’ve typed in, simply hit the arrow keys up or down when in Terminal.

There are a few more less intuitive commands to make the best use of your Terminal history, however.

Quick Look is a fantastic bit of tech, letting you view any file up close and personal with a quick tap on the Spacebar. It works in the Finder, in Open and Save dialogs, and across a ton of other apps like iPhoto.

It’s basically the best new thing ever.

There are times, though, that I forget I’m previewing a file with Quick Look and I head up to the text in a document to copy and paste it elsewhere, only to be rebuffed. You just can’t do this.

Unless, of course, you enable this feature using Terminal.

When you’re typing in Terminal, it’s easy to access the commands you’ve previously typed with the Up arrow on your keyboard. This can be handy when you have to re-type a long, complicated command. Simply hit the up-arrow and you’ll get the previously entered command.

Hit the up-arrow again, and you’ll get the command you entered before that, and so on, cycling through in reverse order until you get to the very first command entered in that particular Terminal window.

Turns out, you can do a similar thing in Messages, too.

OS X offers a very nice graphical user interface to verify and repair your hard drive, located in the Utilities folder. It’s called Disk Utility, and you can use it as the first line of defense when weird disk-related things happen to your Mac’s hard drive.

If, however, you want to dig in a bit deeper, or you’re already running Terminal a lot and don’t want to launch a separate app, you can use the following commands to both verify (check for problems) and repair any problems that you might find when verifying.