Category: General

Find Multiple Filenames By Extension – With Locate

In today’s article, we’re going to explore another way to find multiple filenames by extension – with locate. It’s a handy skill to have and will see you installing ‘mlocate’ to get access to the ‘locate’ command. It shouldn’t be a difficult or even very long article.

If this seems really familiar, then you’re paying attention. After all, it was just a couple of days ago that you saw this article:

How To: Find Multiple Filenames By Extension

So, why are we covering the same topic? Well, WordPress, for legitimate security concerns, likes to eat the slash. (It’s a slash and a backslash. There’s no ‘forward slash’ if you want to be *technically* correct.)

Slashes are understood programmatically, by many programs – including PHP. So, in theory it’d be possible to at least probe for exploits with an unescaped slash. The solution is sort of to escape the slash by including two of them, but then WordPress eats that escaping slash every time you save a draft and add to it!

This is extremely frustrating as an author. It seriously sucks. It’s something I’ll need to keep in mind for future articles, always wary of the dastardly slash! At least now I know…

Well, that hassle of escaping the slash also reminded me that we can accomplish the same thing without any slashes, just by using the ‘locate’ command. With the previous article still fresh in my memory, I figured I might as well write the same article – but with a different tool. Why not?!?

Install mlocate:

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 ‘locate’ command is actually a part of the mlocate package. It’s not always installed by default, but it should be in every default repository out there. It should be easy enough for you to install. 

For the record, the ‘locate’ command describes itself like:

locate – find files by name

Well, that description looks promising – and is exactly what we’re hoping to accomplish! So then, go ahead and install it. You can install it just like you’d install any other software. In the terminal, it’d look something like:

Install mlocate In RHEL/CentOS:
Install mlocate In Debian/Ubuntu:

That’ll work for most distros, assuming you’re using those package managers. If you’re using a different distro, just go ahead and try the same command but adjusted for your package management software. You should be able to find and install it easily.

NOTE: You’re not done yet. The locate command works off of a database. It’s really quick to generate it and it will use a cron job to keep itself updated after that. So, to get the database started, you’ll want to use this command:

With that done, you’re good to go to the next step…

Find Multiple Filenames By Extension With Locate:

Don’t close your terminal from the previous step! Like oh so many articles, this one also requires an open terminal. So, with your terminal still open, you can start to find filenames by extension with locate. For example:

That will find filenames by extension (with ‘locate’) in the current directory. If you want to specify more filenames, it’s really simple:

You can find just one file by extension:

Or you can find a few files by extension:

The sky’s the proverbial limit and the syntax is so much easier. It’s my understanding that the ‘locate’ command is faster because it relies on a database. I ran a couple of tests, using the article about how to time a command and the results weren’t really conclusive – but I only tested with very simple operations. So, your mileage may vary. Feel free to test it and let me know your results!

Closure:

Well, there’s another article. This time, you’ve learned how to find multiple filenames by extension with ‘locate’, and seen that ‘locate’ is a handy command with easier syntax. So, if you’re interested in the ‘locate’ command, be sure to check the man page (man locate). There are many folks who seem to prefer the ‘locate’ command in general, so it seemed like a good article to include.

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How To: Find Multiple Filenames By Extension

Today’s article will show you how to find multiple filenames by extension, using the find command in the terminal. It’s a pretty handy skill to have for when you need to know where files of a certain extension reside on your file system.

If you got a new article notification yesterday, that’s because I’m an idiot. Instead of hitting the schedule button, I hit the publish button. I’m not sure what I was thinking. It was fairly early in the afternoon and I wasn’t even sipping wine at the time! Sorry for disturbing you unnecessarily. I almost sent out an ‘oops’ newsletter, but then I’d have just disturbed you twice.

Anyhow, this will be another article that makes use of the find command. The find command is a rather robust command and can be somewhat daunting for new people. I feel more comfortable writing articles that let you learn it in chunks, rather than trying to cover the entire thing. I do find it hard to explain, but I’ll do my best.

What’s this useful for? Well, let’s say you want to find .deb, .zip, and .iso files in you ~/Downloads directory. That’s what this command is going to do for you. You can find multiple filenames by extension in the terminal and it’s not overly complex once you understand the basics of the command.

Instead of making the intro needlessly longer, and to make up for today’s scheduling gaff, I’ll keep the intro short and we’ll just run straight into the article…

Find Multiple Filenames By Extension:

In the intro, I mentioned that this was going to be done in the terminal. As such, we’re obviously going to need an open terminal for this exercise. To do so, press CTRL + ALT + T and your default terminal should open. Tada!

Warning: I do not explain this one as well as I’d hoped. So, I tried to explain by way of demonstrating. I’m hopeful that works.

Now, here’s the command I just ran in my terminal:

Now, if you want to run it in the current directory, you can specify the directory or you can change ~/Downloads to a . (period).

If you want to find just one file, you’d stop after "*.deb" and leave the closing \).  If you want to add additional files, you would include -o -name "*.<extension>" and make sure to keep the closing ).

It might be easier to show you. For formatting reasons, I’ll use the . (period) instead of specifying a directory. It’ll fit on your screen better than a longer command. So, “How To:”…

Find One File By Extension:
Find Two Files By Extension:
Find Three Files By Extension:

So, hopefully you can see how this find command works. I can’t think of a better way to explain the command than to show it to you in examples. I hope that works for people. Feel free to comment in either direction, as I think it might work for some but be less effective for others.

In theory, you could find all sorts of files by extension, just remember to include the -o -name and file type and noting that the asterisk is a wildcard in this instance, meaning all files with that extension will be found. So, .gz files would be "*.gz". You can make the command as long as your heart desires!

Well, no… There’s bound to be an upper limit somewhere. (Wait, I looked it up, the maximum number of characters in the terminal is 4096 characters. And now we know…)

EDIT: You have no idea how much of a pain in the butt this article turned out to be. Holy crap. For safety reasons, WordPress eats the backslash \. I did not know this. Nobody knows this. The solution is to escape the backslash by using it twice. This article is full of backslashes. I think I got them all. It eats them every time I save the draft, so hopefully they show up in publication. I can never edit this article again, so it is what it is. Well, I could edit it again, but it’d be a pain in the butt.

Closure:

So, yeah… Today we’ve learned to find multiple filenames by extension. At least I hope we have. It’s not so easy to explain, but I figured if I explained it by showing examples then you’d be able to pick it up in context. If you do have any questions, just drop ’em into the comment box below and I’m usually pretty speedy at getting back to people. As always, the man page is probably helpful.

Again, sorry about the fake article notification. That doesn’t happen often, but it does sometimes happen. In an ideal world, I’d have an awesome editor and I would just save everything as a draft. If you’re interested in volunteering for that role, let me know! It’d make my life so much easier, I think… I mean, I don’t really know… It just seems like something that’d help.

Also, I’m pretty excited to write this month’s meta article. I’ll probably wait and schedule it for the holiday or a weekend day. They’re not important articles, but I find it interesting. The site’s growing steadily.

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: Find Files Owned By A Specific User

In today’s article, we’ll be learning how to find files owned by a specific user. We’ll even use the ‘find’ command, as we find files owned by a specific user! That seems to be the best idea, and the best way to do it.

This should also be a fairly quick article. I don’t see any reason why I’d have to make it longer than it needs to be. So, it won’t take too much of your time today.

This article will be published on November 11. That’s a day known by a number of other names. It’s Veteran’s Day, Armistice Day, Remembrance Day, and probably a dozen more names that I don’t know. It was the day WWI ended, which was thought to be the war to end all wars ’cause it was just that horrific.

Well, as you can see, it was definitely not the last war – but we still choose this day to remember. In the US, veterans are celebrated today. Memorial Day is only for those who are no longer with us. Today is for the vets, as well as those who are no longer here.

It’s a holiday, which means it’s a fine day to have a nice and simple article. It’s a fine day to cherish your friends and family, instead of spending your time online reading Linux articles. (But thanks for doing so!)

Find Files Owned By A Specific User:

This article requires an open terminal, like so very many other articles. 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, you should probably navigate to a directory other than your home directory. If you run this command in your home directory, it’s gonna output a whole lot of text. So, let’s just try this first in your ~/Downloads directory:

The command we’re going to use is find, and the format is the find command, a dot to say the current directory, the -user flag, and then the username. So, your command would look something like:

(No brackets, of course.)

You probably don’t have any files owned by root in that directory, so a good test to make sure it’s working properly would be something like:

Now, you can mix things up a bit. Instead of using the dot to indicate the current directory, let’s find files owned by root in the /etc directory.

See? That’s not all that hard at all. It’s remarkably easy to find files owned by a specific user – and the command really isn’t that hard to memorize! You can run it in the folder you’re in, or you can use the directory path method.

Closure:

I told you that it’d be a quick article today. It’s a good day for just a quick tip and everyone can benefit from knowing how to find files owned by a specific user. Toss this tip into your growing list of tools in your Linux toolbox, because  you never know when this will come in handy.

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.

Fix Terminal Command Mistakes

In today’s article, we’re going to cover how to fix terminal command mistakes. While this may sound complicated, it’s actually very easy. As such, it should be a pretty short article. There’s not a lot to it, so it’s not hard to cover.

When you type a command in bash using systems, the command gets saved to the ~/.bash_history file. You can then use the up arrow and use that command again without having to type it again. We’ve also covered how to delete a ~/.bash_history entry. There have been a few articles on this subject.

So, with all that, this shouldn’t be a completely foreign article. It should be something that’s more or less familiar to new people and my regular readers. Because of this, it’s going to be a pretty short article.

Amusingly, it’s not that I want to write an easy/short article today, it’s just that this topic isn’t all that complicated. I was perfectly willing to write a longer article.

So then, let’s have a short article! Let’s learn how to…

Fix Terminal Command Mistakes:

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.

With your terminal now open, type an incorrect command. For example, you could try entering the following command to change to the ~/Downloads directory:

As you can guess, that’s likely to throw some sort of error. The command you’re actually intending to type would have been cd ~/Downloads. Well, you can fix it and run it automatically. Try this:

Tada! It should correct the previous command and then handily run the command on your behalf. To show you what I mean, here’s an image:

correcting an erroneous terminal command
See? It changes ‘cds’ to ‘cd’ and runs the command on your behalf. Pretty nifty, huh?!?

Yup, it just takes a couple of carets and spelling the proper command. It’s not all that hard to fix terminal mistakes. Just to be clear, bash will store both the original mistaken command and the properly fixed command in your ~/.bash_history. But, you can still use the arrow key to go back to either in the future. Of course, you can always delete the bash history entry if you want.

Closure:

See? It is indeed a short article after all. It’s not all that complicated to fix terminal command mistakes, so it’s easy to cover. It’s that how to fix terminal command mistakes is just not something that many Linux users, especially new users, know they can do. Well, you can – and it’s really simple.

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: Compress And Decompress .bz2 Files

In today’s article, we’re going to discuss how to compress and decompress .bz2 files. This is something you may eventually need to know, so I’ll cover it here. I’ll just cover the basics, as most folks won’t need to know anything more than the basics. This should actually be a fairly short and direct article. There’s not a whole lot to it.

If you don’t already know, .bz2 files are bzip2 files. You’ll find that bzip2 is an opensource compression program that gets some regular usage, and you’ll sometimes find downloaded files that are compressed with this format. You may also, for compatibility reasons, want to compress files with bzip2 to share with other users who are already set on using the .bz2 format.

For the curious, the bzip2 man pages define this particular application as (and, as always, I highly encourage folks to read the man pages themselves – this one being a bit more complicated than others):

bzip2, bunzip2 – a block-sorting file compressor

Again, we’re going to just cover how to compress and decompress .bz2 files in this article. That’s all we’re going to do. You don’t tend to come across too many files compressed with bzip2, but they do show up from time to time.

Because of that, we’re going to cover how to compress and decompress those files in this article. It’s gotta get covered eventually, so it might as well be now. Read on!

Compress And Decompress .bz2 Files:

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.

You might actually not have bzip2 installed. It’s not always installed by default. Fortunately, as far as I can tell, it shares the same name in every major distro, that is ‘bzip2‘. So, just go ahead and install it like you’d install any other software. For example, if you’re using Fedora, your command would look similar to:

See? I didn’t use Ubuntu as the default example! We’re mixing everything up today! (Use apt if you’re using a distro with apt, like Debian or Ubuntu and derivatives.)

At this point, you should probably have a .bz2 file to work on for the sake of the article. Seeing as I have no idea what you’ve already downloaded, we should probably start with you making one – just so you can see how to decompress it. 

To compress a file with bzip2, the command looks like (See the detailed warning below this command, do not use this command without reading the warning!):

That will create a file with the same filename but make a .bz2 file. However, this is a destructive act. If you use the above command, the original file will be deleted! If you wish to keep the original file, you need the -k (keep) flag. That looks like:

That command will not remove the original file, as would be the default. Obviously, the -z flag means ‘zip’.

If you want to decompress a file with bzip2, the command looks like:

This will extract the file(s) into the current directory. Of course, the -d means ‘decompress’. This is not a destructive operation. The original and extracted files will remain on your file system.

As you can see, it’s not all that difficult to compress and decompress .bz2 files. You might go years not seeing any files in that format, but you’re eventually going to bump into one and now you know  how to deal with it in the terminal – and how to respond in kind.

Closure:

And there you have it. You have yet another article. We’re getting close to 300 articles at this point, so it has been a long journey. If you feel like writing an article, let me know! Anyhow, you can now compress and decompress .bz2 files easily enough, and that was the point of the article.

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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