Category: Command Line

A Fun Way To Check If Your Network Devices Are Connected

Today is going to be a fun article, mostly good for lazy people, where we discuss a way to check if your network devices are connected. There are far easier ways to do this, assuming you’re local to the device. If you’re not local to the device, the fact that you’re connecting to it likely means that the network is at least somehow connected!

But, in the spirit of being lazy, let’s head into the world of sheer, unadulterated laziness. I mean, if you want to know if your wireless is connected there’s an icon. Of course, you can see if your ethernet is connected. To check that ethernet connection all you probably have to do is look at the back of the computer and maybe wiggle the cable a little bit.

This, of course, presumes that said network adapters are in working condition. If they’re broken, this tool might give you a bit of debugging information. But, still, this is a command that calls itself a “beat connector”. It’s mostly used to check to see if your network devices are connected – as in physically connected to your computer.

The tool we’ll be using will be ifplugstatus and it defines itself as this:

ifplugstatus – A link beat detection tool

At least as far as I use it and the man page indicates, it checks to see if your network devices are connected. Seeing as that’s what the title suggests, it means we’re probably off to a good start!

Check If Your Network Devices Are Connected:

First things first… You’ll almost certainly find that ifplugstatus is not installed by default. You’ll need to install ifplugstatus if you want to use it. To do that, you’ll need an open terminal – which you’ll need for the rest of the article. To open your terminal, press CTRL + ALT + T and your default terminal should open.

Now, I’ve only ever used this command with Lubuntu and similar. Because of this, I don’t know if it’s the same on other distros. (Feel free to leave a comment.) But, at least in Lubuntu, not only is ifplugstatus not installed by default, that’s not the name of the package you need to install. No, that’s a different name and to install ifplugstatus you will want to run the following command:

You’ll need to adjust that command to match the distro you’re using.

Anyhow, with ifplugstatus installed, you can check if your network devices are connected with just the following command:

But wait! There’s more! You can get a lot more information about your network devices by adding the -v (verbose) flag to the command. That flag automatically assumes the -a (all) flag, so it’s just:

There you have it… Instead of just looking in the status bar section to see if wireless is connected, or even looking around the back to see if the cable is connected, you can just check all that right there in the terminal – without having to move much more than your hands! You’re welcome!

Closure:

Heh… There you have it! You have another article. If you ever want to check for a beat, that is to check if your network devices are connected, you now know how to do so. You can even SSH into another device and check to see which of its network devices are connected (beyond the obvious one you’re connecting with). You don’t even have to leave your seat.

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How To: Prevent A File From Being Deleted*

Today, we have another simple article, where we discuss how to prevent a file from being deleted. It’s not quite true and I’ll explain in a moment, but for the most part, it makes it so you can’t remove a file by accident or the like.  So, if you want to prevent a file from being deleted* read on.

Now, let me be more clear. I’m a bit sorry for the cheesy headline, but there’s a reasonable character limit. I included an asterisk just to make sure. A user with root permissions (eg a user with sudo privileges) can still delete the file – but it takes an extra step to do so. They have to know and work at it to delete the file.

The tool we’re going to use is called chattr. While it looks like ‘chatter’ and I want to type ‘chatter’ every time I use it, it is a tool that you use to change a file’s attributes. It’s a handy tool but we’ll only be examining one specific use for chatter. If you’re curious, the man page defines chatter as:

chattr – change file attributes on a Linux file system

If you’re using a mainstream distro, you shouldn’t need to install chattr. You should find it already installed. Some of the more lightweight distros may not include it by default, but you can verify that it’s installed by running the following in your terminal:

If you do find that chattr isn’t installed, go ahead and install it. It’s in your default repos. I’m sure of it!

Prevent A File From Being Deleted:

You guessed it. You’ll need an open terminal for this one. That’s easy, just press CTRL + ALT + T and your default terminal should open. See? Pretty easy!

Now, I’m going to show you how to use chattr to set an immutable bit. It’s not difficult and just uses the +i flag. Let’s start with creating a file:

With the file created, let’s set the immutable bit with chattr:

Now, let’s try to remove it with the rm command:

No luck? Well, let’s grab a hammer. We’ll try to remove the file with sudo:

Surprise! You still can’t delete it, even with sudo or logging in as root. To delete the file, you have to first remove the immutable bit, like so:

After that, you can happily (and trivially) remove the file with:

In case that’s not very clear, I’ve made you an image. That should help!

prevent a file from being deleted
See? If the words aren’t useful, perhaps the picture will explain it better.

That should explain it well enough. The file can still be deleted, it just requires sudo and removing the immutable bit from the file’s attributes. Pretty neat, huh?

Closure:

Of course, there’s always a way for a root user to be able to remove a file. However, you can make it difficult should you want to prevent a file from being deleted. A skilled user will check the file’s attributes and know how to delete the file, so it’s more about protecting a file from being deleted unless you want to.

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Let’s Update Ubuntu In The Terminal

Today’s article will be a nice basic article, where we discuss how to update Ubuntu in the terminal. It seems like a fine article to write and one that not everyone will be versed in. There are lots of folks who don’t use the terminal for much of anything. Then, there are people like me who use the terminal for all sorts of stuff.

If you know how to update Ubuntu in the terminal, this really won’t be a very interesting article. We’ll just be covering the basics and I’ll explain how I do it. You’ll see that I tend to throw caution to the wind and just blindly hope for the best. This strategy is fine for me, ’cause I can fix pretty much anything. (I can fix pretty much anything because I’ve broken pretty much everything.)

Of course, this article applies to Debian. This article applies to Linux Mint. This article should apply to anything that uses apt as the package manager. So, if your distro is related to Debian then this will probably work just fine for you.

Well, there’s no reason to make the intro any longer… I think I’ve covered all that you need to know to get started.

Update Ubuntu In The Terminal:

As you can guess, we need an open terminal if we’re going to update Ubuntu in the terminal. That only stands to reason… Press CTRL + ALT + T and your default terminal should open.

With your terminal now open, let’s update the list of software that’s available. Let’s see what software can be updated. To do that, you just run:

That will tell you the software that’s available to update. You can see what those updates are with the following command:

You can then upgrade those applications one by one if you want to. Some cautious people do this. Some businesses do this – and do this to a staging environment to test – ’cause they need to keep things running. If you want to upgrade just a single package, try this:

Now, most folks are probably going to want to upgrade all the software that has new versions. They get it easy, they just type:

This will give you the chance to see everything that’s going to be upgraded and the chance to decline or agree. Me? I automatically agree. You might want to be more cautious, but I like running the command closer to this:

That automatically says yes that I’d like to upgrade all the things. After all, even if stuff were to break, I’d have had to have upgraded to find it anyhow. 

I go a step further and just tie the two commands together. The command I run would look closer to this:

That will find all the available upgrades and install them automatically, that is without any further input from me. I’ve done this for years and it hasn’t been a problem or any more of a problem any other method would cause me. So, in short, that works for me.

Closure:

I don’t know that you wanted to learn how to update Ubuntu in the terminal, but that’s today’s lesson. It’s not very complicated. I could keep going, as my actually command also includes the ‘clean’ option. I use an alias to tie it all together, rather than typing it out each time. There are also similar commands you can use for other distros with different package managers.

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Use Tab Autocomplete In The Linux Terminal

Today’s article isn’t all that complex or anything, we’ll just cover how to use tab autocomplete in the Linux terminal. It’s a pretty handy tool to have in your Linux toolbox. It’s especially handy if you spend a lot of time in the terminal.

It seems to me that tab autocomplete is easier to do than it is to explain. It’s a great concept. I asked ChatGPT to explain it on my behalf and it did a fairly good job. It’s the middle of the night and I almost forgot to do an article. I got distracted, ended up elsewhere in the house, and fell asleep.

Fortunately, I already had the headline written. (Coming up with ideas is often more time-consuming than writing some articles.) That was a good thing. Otherwise, I’d have gone back to sleep and just written this tomorrow.

Anyhow, tab autocomplete is a tool that WILL save you some time. If you were local to me, it’d take like 2 minutes to show you how autocomplete works. It’s gonna take a bit longer to explain it with text!

I suppose that’s an adequate intro. Let’s see how AI does at explaining tab autocomplete and then try to make it more clear below that:

Use Tab Autocomplete In The Linux Terminal:

Linux terminal tab autocomplete is a feature that allows users to quickly and efficiently navigate through the file system and execute commands without typing out the entire file or command name. It works by automatically completing a partially typed file or command name when the user presses the “Tab” key.

To use tab autocomplete, the user needs to start typing the file or command name in the terminal window and then press the “Tab” key. If there is only one file or command that matches the typed characters, the system will automatically complete the name. If there are multiple matches, the system will display a list of possible options. The user can then continue typing until the desired file or command is highlighted and press “Tab” again to complete the name.

Tab autocomplete can be used for a variety of tasks, such as navigating the file system, running programs, and passing arguments to commands. For example, if the user wants to navigate to a directory called “Documents” in their home directory, they can type “cd Doc” and press “Tab.” The system will automatically complete the name to “cd Documents/”. This can save the user time and effort compared to typing out the full path.

Tab autocomplete also supports wildcards, which can be used to match multiple files or commands with similar names. For example, if the user types “ls *.txt” and presses “Tab,” the system will show a list of all the files in the current directory that end in “.txt”.

In summary, Linux terminal tab autocomplete is a powerful feature that allows users to quickly and efficiently navigate the file system and execute commands without typing out the entire name. It saves time and effort and can be used for a wide range of tasks.

Additional Tab Autocomplete Stuff:

So, to put that information to use, we can open a terminal. You can do so now just by pressing CTRL + ALT + T.

With your terminal now open, try the following command:

Now, press the TAB key on your keyboard (you may need to press the tab key twice). You’ll see something like this:

use tab autocomplete in the Linux terminal
You can probably figure it out from here. Once you understand it, you’ll appreciate it.

As you can see, it was not able to autocomplete because there were two available choices. If there are no choices it will show nothing. In this case, if you want to change to the Downloads directory, you’d enter the following:

Press the TAB key (probably twice), of course. For most of you, that’ll be enough. If it’s not, you should be able to figure out the minimum number of characters needed for autocomplete to work.

This also works on commands, but you need to have narrowed it down or it needs to not start with the more common letters. How to explain it?

If you type ‘l’ and hit tab, nothing will autocomplete.

If you type ‘ali’ and hit tab, it will spot autocomplete to ‘alias’. Additionally, it works for your installed applications. If you just enter ‘l’ and press the tab key (twice, if once doesn’t work) it will offer to display a bunch of commands starting with the letter ‘l’. For many of you, you should be able to just type ‘pav’ and then press the tab key to have it autocomplete to ‘pavucontrol’. That should make it reasonably clear.

Closure:

See? It’s not hard to do. It’s easier to do than it is to explain. I’ve never really needed to properly explain tab autocomplete in text format before. It’s much easier just to physically show folks than it is to explain it in text. Hmm… Now I can go back to bed. Dunno if I’ll sleep again, but I might as well try.

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Find Out What A File Is

Today we’ll have a simple article, one that shouldn’t take too long, as we learn one way to find out what a file is. It’s a handy command, but it won’t take all that long to explain. So, we’ve got that going for us!

The command we’re going to use is one that you almost certainly have installed by default. That command is the ‘file’ command. The man page describes file as:

file — determine file type

Linux pretty much treats everything like a file, pretty much. Files also contain a ‘magic number‘ – which is why you can rename an mp3 file as a gif file and it’ll still open in your media player. Basically, the magic number is the opening two bytes of a file that tell your system what kind of file you should be expecting. 

If you change the file extension it won’t fool the ‘file’ command. You can rename it with any extension you want and ‘file’ will know what the file is. Of course, it might be a text file, a compressed file, a Debian installer, etc… There are all sorts of file types out there. There are hundreds of file types just for image files.

So, yeah… We’ll be using the file command in this exercise. Let’s get to it!

Find Out What A File Is:

Like oh so many other articles, this one requires an open terminal. We do a great deal in the terminal. You can press CTRL + ALT + T and your default terminal should open.

With your terminal open, you’re probably in your home directory. So, the vast majority of you should be able to run the following command:

That file contains a bunch of the settings you see affected in the terminal. As you can see from the output, it’s an ASCII file, meaning you’d edit it with an ASCII (plain text) editor.

If you want, you can navigate to your Downloads directory and use ls to list the files. From there, you can run the file command on files you’ve downloaded. For example, I could run:

The output from that command would look like this:

The file command knows what the file is. It’s pretty accurate. It doesn’t matter if I change the .deb to .gif. 

See? Renaming the file didn’t fool the system. However, it might fool some applications. For example, if you click on that “.gif” file, your system might try to open it as an image and throw some sort of error. The file command can be pretty handy in those situations, where you’re not sure what the file type is and how you should approach it.

Closure:

Well, if you ever wanted to find out what a file is, you now know how. Over your computing journey, you may very well find you need to rely on the file command to know what the file type is. It’s a pretty handy command for when you need it. Of course, you could go so far as to edit the magic numbers to fool the command, but you’d probably know if you did that.

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