Tag: power management

Let’s Reboot Your Linux Computer

Today is another article with one of those things you probably already know, it’s about how you can reboot your Linux computer. Specifically, we’re going to reboot from the terminal. You can use the GUI to reboot easily enough, but if that’s frozen and you don’t really want to do a hard restart, you might as well reboot it if you can.

If you can’t reboot your computer because it appears frozen, consider the Magic SysReq Keys. (More specifically, the REISUB method.)

If you aren’t already aware, there are all sorts of ways to reboot your Linux computer. Like oh so many things in Linux, there’s a multitude of ways. We’re just going to cover a few of them, because you really don’t need to know more. Well, if you do need to know more,  you probably already know those ways to reboot your Linux computer!

It’s also another fairly simple article. That’s good (for me) as it’s a bit like work lately and I don’t want the site to really be about work but rather being about a hobby. If it’s work, I wanna get paid… 

This is also useful information if you’re working on something remote. You don’t want to shut that system down and have to have someone go physically turn it back on, so you reboot the system – making sure to reboot the right system and not the system you’re physically using. I’ve done that more times than I care to share – and I’ve done the reverse as well. It’s seldom good if you enter the reboot command and immediately follow it with a verbal, “Oops.”

Reboot Your Linux Computer:

This article requires an open terminal, because we’ll be learning how to reboot your Linux computer from said terminal. If you don’t know how to open the terminal, you can do so with your keyboard – just press CTRL + ALT + T and your default terminal should open.

With your terminal now open, let’s start with the easiest of the commands to reboot your Linux computer:

With some distros, that’ll be all you need. With others, you may need to have elevated permissions. This is also often true if you’re connected remotely, via SSH. So, in those instances, you’ll need to preface it with sudo and use your password when asked. Like so:

If you want,  you can also use the shutdown command. That’s pretty easy, you can just use:

The -r flag tells the system to reboot and the ‘now‘ means to do so right now – immediately. You can play around with that ‘now’ bit, like so:

Instead of ‘now‘ you’ll see there’s a ‘1‘ and that’s how many minutes you want to wait before rebooting the system. You can change that to any number you’d like, I suppose.

Finally, you can use systemd to reboot. Why? Because of course you can! It’s systemd, and you can do anything with it! (Kinda like zombo.com, I guess.)

That’ll happily reboot your Linux computer, all nice and neat and proper. It does exactly what you’d expect it to do, so there’s that.

Closure:

There you have it. You now have a few ways to reboot your Linux computer from the terminal. There are other ways, including init or whatnot. You can also just use the GUI if you’re working locally. It’s Linux. There are all sorts of ways to accomplish a given task. That’s a good thing.

I find myself rebooting from the terminal more often than not, simply because I’ve already got a terminal open and it’s just as quick for me to type the reboot command as it is for me to go clicking around. I’m also often testing other systems and really don’t want to have to go fishing around to find the command, then click on some sort of secondary agree menu or the likes.

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Let’s Learn About Halt

Today’s article is about the halt command. The reason we’re writing about the halt command today is because I was halfway through another article before I realized I’d already written an article on that subject. So, this is going to just be a nice, easy article.

And, yes, yes I did write more than half of an article that I’ve already written. I ain’t even intoxicated!

The command we’re looking at using today is called ‘halt’. For such a little command, here’s an interesting post about the difference between halt and shutdown. And, if that’s not enough, you can read the other answers and comments on that page. 

Anyhow, halt is described like this in the man page:

halt, poweroff, reboot – Halt, power-off or reboot the machine

Of those three, we’ll just be covering the halt. Yes, the man page contains all three in just one page. They’re all related. As I said, we’ll just be covering the useful features of halt command today.

And, without further ado…

The Halt Command:

This article requires an open terminal, like many other articles on this site. If you don’t know how to open the terminal, you can do so with your keyboard – just press CTRL + ALT + T and your default terminal should open.

Once you have the terminal open, the first use of halt would be just to halt the system:

That will halt your CPU. It probably won’t shutdown your computer all the way, it will just stop it. So too won’t the -f (force) flag. If you force it, it just stops the CPU. It looks like and requires sudo:

Finally, of the options we’ll cover, is the -p flag, and the -p stands for poweroff. It’s just another way to shut down your computer, and it obviously looks like this:

Those are about the only ways you’re ever going to use it, if you use it at all. It’s not a command that you’re likely to bump into but now you know it exists and how to use it.

Closure:

There you have it, another article. This one covers the halt command in Linux. It’s not a major article, but I needed one in a hurry – just to ensure there’s one scheduled. While my health is mostly returned, I’m still not so caught up that I have a bunch of extra articles. Feel free to step up and write one or two!

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How To: Shutdown Linux From The Terminal

Today’s article is going to tell you how to shutdown from the terminal. I’ve previously explained how to reboot a ‘frozen’ Linux system using the Magic SysReq keys. Today, we’ll shutdown from the terminal. It’s a quick and easy article – as the holidays are eating a bit of my “free” time.

Why would you want to do this? Well, if your Linux system isn’t quite frozen or your desktop GUI isn’t something you can reach, then you may want to press something like CTRL + ALT + F3. That should crack open a TTY where you can login and issue commands to your system. Maybe you’re working on a server and need to shut it down? Who knows, but the command is there and it’s a useful command to keep in mind.

For this article, we’ll mostly be using the shutdown command, and the man page defines it as:

shutdown – Halt, power-off or reboot the machine

And it does pretty much what you’d expect from such a command. However, it’s not just a basic command, there are flags and some options that go along with it. So, we might as well take the time to learn about it. After all, you never know when you want to shutdown Linux from the terminal.

Shutdown Linux From The Terminal:

Like oh so many articles, this one will require an open terminal. If you’re connected to a remote server via SSH, you already have a terminal to work with. If not, just press CTRL + ALT + T and your default terminal should open.

Once you’re ready to shutdown your Linux system, you can enter the following to shutdown immediately:

Obviously, that command will shutdown the system immediately, so don’t practice it unless you plan on shutting down – ’cause you will. You can even shutdown at a specific time by using this format (and 24h time):

You can also use the +MM function. To shutdown in 10 minutes, you’d use a command like this:

If you change that +10 to +0, it will also shutdown immediately. If you have users of the system who should be notified of an impending shutdown, then you can actually send them a message. That would look like:

So, what happens if you schedule a shutdown and need to stop it for some reason? Fortunately, the shutdown command will let you cancel an impending shutdown – so long as you get there in time. That’s done with the -c flag, of course.

If your cancellation will impact the users, you can even include a message in that. It’s done like this:

And that’s about it, really. There’s a bit more to the shutdown command, but it’s mostly going to be used in one of the ways mentioned in this article. If you want more information about the shutdown command, simply run man shutdown and read the help file.

Closure:

And there’s another article. This one will tell you how to shutdown Linux from the terminal, a handy skill to have as a user or as an admin. It may seem like a pretty basic command, but that doesn’t mean it can’t be included on the site. 

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When Did I Last Reboot My Linux Box?

If you want to know when you did your last reboot on your Linux box, it’s actually pretty easy. This article explains how. I’m still not feeling quite up to snuff, so a quick and easy article is the call for the day!

You can run uptime in the terminal, and that will tell you how long your system has been up and running. The output will look something like this:

At this point, you could do the math and find your last reboot time. Of course, this being Linux, there’s an easier way to do this. This will be a quick (and easy) article and hopefully I’m doing a bit better tomorrow.

Find Last Reboot:

Like so many of these things, we need to start with the terminal open. You can do that by using your keyboard. Just press CTRL + ALT + T and your default terminal emulator should pop right up!

With that open, you can start with:

Which will give you an output similar to:

But, the command’s usefulness doesn’t stop there. No, no it does not! You can modify the command in a couple of ways to get some more refined response. Let’s say you only want the last three results? If so, you’d use this command:

This will give you an output like this:

You can also use ‘grep’ for your refining needs. Let’s say you want to know when you last rebooted in the month of May? Well, you can easily do that!

The output of which would look similar to this:

And, there you see it. As you can see, there were three reboots in the month of May on that box. This information may be useful for debugging reasons or even compliance reasons. How you use the information is up to you! Ain’t my job to tell you how.

Closure:

There. There’s your darned article for the day!

Seriously, yesterday’s article was really messed up. Fortunately, the kind folks at Reddit chimed in and were eager to help! The folks at Linux.org are usually good at catching the mistakes, of which there were many, but probably didn’t as the article is one from the old site and probably only skimmed it if they read it at all.

This leads me to think that I’m eventually going to have issues with getting an article up every other day. I’m still going to try, and I’ve done so since the start, but it’s pretty likely that I’ll eventually miss a day. I’ll try to take steps to not let that happen, but the real world is a fickle mistress.

Thanks for reading! If you want to help, or if the site has helped you, you can donate, register to help, write an article, or buy inexpensive hosting to start your own site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

How To: Disable Sleep And Hibernation on Ubuntu Server

For some reason, Ubuntu Server comes with ‘power management’ enabled. This is an article that tells you how to disable sleep and hibernation in Ubuntu Server. It’ll work just fine for non-server installs, but this is aimed specifically at the Ubuntu Server release.

I recently was working on my own router. For this, I used Ubuntu Server as the base operating system. For some reason, it was shutting itself down after periods of inactivity. This isn’t acceptable behavior for a device that’s meant to be running all the time.

I checked in my logs and I found entries like this one:

Apr 3 12:18:27 server systemd[1]: Reached target Sleep.

That was entirely unacceptable. I do not know why power management was installed, nor do I know why it was active by default. I merely know that it was and that I couldn’t have that behavior with a server, a device meant to be always powered on.

So, I did what anyone would do in my shoes. I disabled sleep and hibernation entirely. It’s quick and easy – and effective! I’ll show you how!

Disable Sleep/Hiberation:

Like most articles, you’re gonna need a terminal. If it’s actually a server, you’re likely already able to connect with SSH. So, add the step of connecting to the server if you’re doing this remotely. If not, just proceed.

Once you have your terminal open, you’re to kill everything that has to do with suspend, sleep, or hybrid-sleep. It’s actually pretty easy. Start by opening said terminal, by pressing CTRL + ALT + T and then enter the following commands:

First, you mask ‘sleep.target‘:

Then mask ‘suspend.target‘:

And mask ‘hibernate.target‘:

Finally, mask ‘hybrid-sleep.target‘:

Later, should you change your mind, you can unmask them and that’ll enable them again. Just change ‘mask’ to ‘unmask’ and run the commands again. See? Pretty easy!

If you want, you can verify the efficacy. Simply use the following:

(You can change ‘sleep.target’ to one of the above services and check them individually.) 

Closure:

That’s it! I told you that it’d be pretty easy. It’s not only easy, it’s easy to undo this should you change your mind. Again, I do not know why power management is enabled by default in a server release. Nobody asked me! So, that’s how you disable sleep and hibernation with Ubuntu. (It’ll surely work with other distros.)

Thanks for reading! If you want to help, you can donate, write an article, vote for articles you like, share this article on social media, buy cheap hosting, register to help, etc… Nobody ever reads the last paragraph anyhow. Still, you can help if you want!

Update 01.27.2020 Per comment.

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