Category: Command Line

Turn Your Ubuntu Into A Wireless Hotspot

Have you ever wanted to use your Linux computer as a wireless hotspot? It’s actually pretty easy. Today’s article will get you started and it really isn’t all that difficult. We will actually be cribbing a bit of this article from the software’s homepage, but while some more, rather important, information added.

For many years, I used my own router that I had configured on my own hardware. It was built on Linux. The preceding version actually ran on BSD, but that’s not important for a site called Linux-Tips. Today, you can get a NUC or Pi for dirt cheap and so making a new router is back on my list of things to do. In other words, it’s a fun project that won’t take a lot of money to get into.

All of the varied software and hardware components are already there to make your own router, but I want to enable wireless connectivity. a wireless hotspot, and that’s what we’re going to look at today. The tool we’re going to use is called ‘linux-wifi-hotspot‘ That’s is a great tool, complete with GUI if wanted, written by lakinduakash. It has only been around for a few years, but it’s spoken of very highly – and it just works and works well.

At least it worked the last time I used it. This article is from the old site and I’m just moving it to this site. I actually haven’t bothered much with my own router for the past year or so. So, this information is a bit dated.

Turn Your Ubuntu Into A Wireless Hotspot:

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.

The software is easy enough to install. If you’re using Debian/Ubuntu, just add the PPA and install the software. To add the PPA, you just run:

On a modern Ubuntu, you shouldn’t need to do this, but you might want to go ahead and run a quick update with:

Then you can install the software, starting to get your system into a workable wireless hotspot. To do that, it’s just:

If you want, you can visit the link above (in the preamble), click on releases, and download the .deb file for the current release and just install it with gdebi. In this case, I’d suggest installing with the PPA – just to make sure

Then, you can go ahead and start it. You can also go ahead and make it start at boot, which would be prudent if you intended to use this to make your own router. It’s really self-explanatory and without specific questions for using it, I’m just going to refer you to the man page and the information at the project page.

Caveats:

But, before you can even do all of this, you need to know that your wireless adapter actually supports doing this. To find out, you need to know if your wireless adapter supports “AP” mode. AP obviously meaning ‘Access Point’.

To check this, you need to run the following command:

The project page is noticeably silent with this, but it’s a necessary step. See, you need to know if your hardware actually supports it before you even bother trying. Come to think of it, I probably should have put this closer to the top of the page! Ah well…

Anyhow, the output should contain one or both of the following lines:

Device supports AP scan.

And/Or:

Driver supports full state transitions for AP/GO clients.

So long as you see one or both of those, you should be all set to proceed. If you don’t see either of them, there’s no software solution and you’ll need to get hardware that supports AP mode. In many cases, that’ll mean doing a bunch of research and may even mean contacting the vendor or OEM.

Nobody appears to have compiled a list of hardware that supports AP mode and I don’t think I’ve ever bought wireless adapters that explicitly stated they do on the box. As near as I can tell, more modern adapters support it just fine, so you’ll probably be alright. Online specs are more thorough than what’s printed on the outside of the box, so maybe searching is okay.

Closure:

Alright, there’s your article for the day. I have no idea if you want to make a wireless hotspot for your Linux box, but now you know how. It’s pretty self-explanatory, and you shouldn’t have any questions. If you do, you know where to find me – or to find others who can help you – at Linux.org.

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Change Ownership Of Files And Folders

Today, we’ll be covering how to change ownership of files and folders. This is a pretty basic task and one every Linux user should know. This needn’t be terribly complicated, so this article will explain all you really need to know about changing ownership of files and folders.

When dealing with file management, permissions are important. It’s a security matter and a usability matter. You can assign various file and folder permissions, such as read and write permissions, a subject for a different article. However, files and folders all should have owners – owners who can do anything they want with the file or folder.

Curiously, your account should not always be the owner. While maybe not all that intuitive, you shouldn’t have ownership of all the files. This is why you have to use elevated permissions to perform certain tasks. This is to keep things segmented and secure.

Remember, Linux is designed to be a multi-user operating system. That’s not just human users, but different processes and applications may also be associated with users. For example, look at all the users on your system by running the following command in your terminal emulator:

You can also see all the groups on your system with this command:

Obviously, if a user is a member of a group they share permissions with that group. Files also only have one owner and one associated group, of course. So, if you want two people to have control over a file, one way to do that would be to make sure they’re both members of the same group. There’s all sorts of creative things you can do with permissions. This article will be covering just one aspect, it’ll be about how you can …

Change Ownership Of Files And Folders:

Like oh so many of these articles, this one requires an open terminal. You can do so using only your keyboard – just press CTRL + ALT + T and your default terminal should open.

Go right ahead and stay in your home directory. You can check the various files and their permissions with the following:

The output of that command will show you the user and group, with the two being listed in that order as in the image below:

ll listing user and groups
See? I even gave you handy arrows. The order is owner:group, to repeat myself.

To change the owner, the format is:

To change the group, the format is:

If you want to recursively take ownership, you need the -R flag. For that, you’d want something that looks a bit like this:

You can actually just use chown to change both the owner and group at the same time. You’ll most often do this with your own user and group, so I’ll show the command that way:

As you can guess, the -R flag will work there and an asterisk will cover all the files and folders within that directory. Obviously, this applies to folders and not to files.

Closure:

There you have it. You have yet another article and this one has hopefully taught you how to change ownership of files and folders. It may not be one of the most interesting articles, but it’s a skill you’ll eventually want to have and another tool for your Linux toolbox. 

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: Show Hidden Files And Folders

Today, you’ll read an article that tells you how to show hidden files and folders (in Linux, of course). This is something everyone should know. This is a basic skill that you’re almost certain to need if you make the decision to use Linux.

Fortunately, it’s pretty easy to show hidden files and folders. You’ll see…

First, I should probably explain what hidden files and folders are. They’re files and folders that start with a period. So .foo.txt is a hidden file and .bar could be a hidden directory. One should remember that Linux is, by design, a multi-user system. With that in mind, having hidden files makes sense – if you don’t want those files to be accidentally (or maliciously) edited.

Any files or folders that begins with a period will be a hidden file. If you’re new to Linux, you might want to leave them hidden until you’re a bit more comfortable working with system files. Or not… It’s your system, you do what you want with it.

In a GUI file manager, you can usually figure out how to show hidden files and folders pretty easily. Sadly, it’s not universal in a GUI. Look in the right click menu, under the “View” option, or in the application’s preferences. It’s also often ALT + H and I want to say I’ve even seen it be ALT + F4. Look around, you’ll find it.

This article is more about showing those hidden files and folders in the terminal. It’s a really easy command and won’t take too long to explain it to you. So, enough preamble, let’s begin.

Show Hidden Files And Folders:

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.

We’ll stay right in the default directory, your home directory. If you’re not currently in your home folder,  you can get there with:

Your home folder should have all sorts of hidden files and folders. First, let’s see your home directory without showing the hidden files and folders:

Unless you’re in the habit of storing files in your home directory, you should have a fairly tidy list of folders and files that you’re likely already familiar with. 

Now, let’s try again – this time showing hidden files and folders:

Or, you can get a more easy to read output with this command (and you get more information with it):

If you want to see it in action, you can try this command:

Now, if you use the ls command you won’t see that file. If you use the ls -a command you’ll see the hidden file that you created called .foo.txt. This of works with directories, as they too can be hidden.

Yup, that’s it. That’s today’s article. See? I told you it was easy.

Closure:

Indeed, it is an easy article – and one most of my readers will already know. This one is aimed squarely at the new user who has yet to learn how to show hidden files and folders. It’s a pretty important skill to learn, and it’s also important to know which ones you probably shouldn’t edit. So, judicious use is important.

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How To: Free Some Disk Space By Deleting Old Logs

In today’s article, we’re going to free up some of your disk space by deleting old logs. It’s a relatively safe and easy thing to do, and can free some space up if you’re running low. Unless there’s a problem, you really don’t need a bunch of old logs kicking around and taking up space.

There are other reasons for deleting old logs, such as keeping things tidy or even ensuring old activities aren’t easily discovered by browsing old log files. You may have done some debugging and now want to start with a new slate, so there’s another reason to delete logs. 

Who knows what motivations you’ll have, but today we’ll be covering how to do it. The tool we’ll be using for log cleaning is ‘journalctl’, which is used for (according to the man page):

journalctl – Query the systemd journal

While ‘journalctl’ is a pretty nifty tool, we’re only going to scratch the surface. This article is only about deleting old logs and ‘journalctl’ is just the tool we’ll be using. If you want an article about all the features of ‘journalctl’, this is not that article. See? I’m saving at least a few people some time!

Anyhow, this article obviously requires a distro that uses ‘systemd’. If you don’t have ‘systemd’, you probably don’t have ‘journalctl’ and you’ll have to find another way to delete your logs. As most mainstream distros are using ‘systemd’, there’s a pretty good chance that you have ‘journalctl’ available.

So, with all that preamble gibberish out of the way, let’s go about …

Deleting Old Logs:

Like oh so many articles here, this one requires an open terminal. Why? Because of course it does. 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.

Now, with your terminal open, let’s have a look and see how much space your logs are taking up. You can do that with this command:

Now that you’ve seen how much space your logs are taking up, there are a couple of commands you can use for deleting old logs. If you want to go by space, you can use this command:

You can edit the ‘100m’ to whatever suits your needs. You can also use ‘g’ for gigabytes if you’d like to keep using that much log space.

If you want, you can also delete your old logs by the day. Let’s say you want to retain the last 3 days of logs. Well, that command would be:

I suspect you can figure out that the ‘d’ stands for ‘day’ and the 3 is how many days. You can, of course, change that to any number of days you wish. If you want, you can even use ‘w’ for weeks. Though, if you’re deleting log files to clear up disk space, you’re probably going to want to trim the logs even more than that.

Anyhow, when you’re done running one of the cleaning commands from above, you can verify that the space has been cleaned by running the very first command listed. That will do exactly what it did the first time you ran it – it’ll tell you how much space your logs are taking up. If they’re still not small enough for your liking, feel free to edit and run one of the above commands a second time.

Closure:

Well, there you have it… You have another article! This time I tell you how to go about cleaning old logs from your system. It’s a handy skill to have, though most folks probably have ample disk space – except those running on stuff like Chromebooks or the likes. If you’ve gotta live within 16 GB, you’re going to want to keep your logging to a minimum. Also, I still haven’t skipped a day from writing articles. It seems likely that I’ll do so eventually!

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Let’s Use ‘netstat’ To Find Out What Process Is Listening On A Specific Port

Today’s article is going to teach you how to use ‘netstat’ to find out what process is listening on a specific port. If you have open ports and don’t know why – and what’s listening on that port, you’re not making good security choices.

Let’s say you followed an article about how to monitor TCP/UDP in real time. If you’re new, or even just not all that advanced with Linux and networking, you might not know why there are all those ports and all that activity. Well, one of the things you should know is how to identify what process is listening on a specific port.

There are a number of ways to do this, but we’ll be using ‘netstat’. The ‘netstat’ application can be pretty advanced, but what we’ll be doing is pretty straightforward. If you’re curious, ‘netstat’ defines itself thus:

Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships

As you can see, it’s a pretty advanced application. It has a rather expansive man page, and we’ll largely ignore that as we really only need some limited functionality. All we really need to do, for this exercise, is find out what process is listening on a specific port.

With that in mind, let’s leap into the meat of the article…

What Process Is Listening On A Specific Port:

This article requires an open 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.

Once you have that open, you’ll need to find out if you have ‘netstat’ already installed. There are many ways to do this, I prefer:

If you do not have ‘netstat’ installed, it’s certainly available for all mainstream distros and easily installed from your default repositories. Here’s how to install on a few distros:

Debian/Ubuntu/Mint/etc:

RHEL/CentOS/Fedora/Rocky Linux/etc:

SUSE/OpenSUSE/etc:

If you’re using a different distro, root through the default repositories. It’s a pretty common tool and I’d like to imagine it’s easily available to anyone.

Once you have ‘netstat’ installed, the command we’re going to use is really, really, simple. In fact, I wrote this whole darned article mostly for just one command. I probably could have made it shorter. Still, it might as well be long enough to give some extra information along the way.

Anyhow, the command you run is this:

For example, you might have an open port 22 and want to know what process is listening on that specific port. So, you’re command would look like this:

The end result will look something like this:

netstat being used to find out which process is listening at a specific port
While not completely clear, you can deduce that it’s just the SSH daemon listening on port 22.

It may not be completely clear, but you can use this to deduce what process is listening on a specific port. If it’s not completely clear, you can get actually dig a little deeper. See the “1100” in there? Well, that’s the PID (Process ID) and you can use the following command to get more informtion. It looks like this:

The output from that in this case is:

Which, as we know, is the daemon for SSH and thus nothing unexpected is running on port 22. See? Security!

Closure:

And there you have it, another article. This one is a pretty handy one, especially for when you want to know what process is listening on a specific port. If you have things running that you can’t identify, you can always stop by Linux.org and ask for help. Someone there will try to find out what’s going on for you.

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.

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