Category: General

PDF Exif Data

Yes, this is another PDF article, but this time it involves a bit of privacy or security because there’s such a thing as PDF Exif data. This shouldn’t take all that long and it shouldn’t be all that complicated.

Files have Exif data. Well, many files do. You’ll find Exif data in your image files, document files, and even PDF files.

Exif data is metadata. It can contain information about when the file was created, how it was created, and when it was modified, among other things. This is useful data but you may still want to know it exists. Additionally, you may want to change it.

I’ve covered Exif data in the past. Exif stands for Exchangeable image file format and is used in many different ways.

Here are some other Exif articles:

How To: Sanitize Exif Data From Your Digital Images For Privacy Sake
Short: Show File Creation, Modification, and Access Times
Review: MetaClean (Clean Exif/meta Data From Email Attachments Automatically)

So, this isn’t a foreign concept. There are other Exif data articles, but this one is specifically for PDF files. We will need some software for this and that software is ‘ExifTool’…

ExifTool:

The tool we’ll be using in this article is known as ‘ExifTool’ and it’s a widely available application. The ExifTool application is used to view the metadata from a wide variety of file types.

If you check the man page, it should describe ExifTool as such:

exiftool – Read and write meta information in files

You should check the man page once you have ExifTool installed. You do that with the following command:

The list of things ExifTool works with is why you should check the man page. It’s rather extensive and it may surprise you how much metadata is kept in a file. It’s a lot and this is the correct tool for the job.

Let’s see if I can fit the man page into this article to show you how many file types contain meta information that you may not be aware of…

These are the types of metadata that ExifTool can interact with:

That’s not as well-formatted as I’d like, but it will have to do. It’s a lot of information and I’m not going to invest more effort than I have already invested in this. It’s just a code block, which should work well enough.

So, ExifTool is quite extensive and we only need it for PDF Exif Data!

Seriously, this is quite a tool. It’s something you may want to be familiar with.

PDF Exif Data:

This ExifTool is a terminal-based application. That means you’re going to need an open terminal and a PDF file to work with. You can start by pressing CTRL + ALT + T to open your terminal.

You’ll need to install ExifTool. The command will vary based on your distribution’s package manager. It should be available for the major distros and I’ll cover some of those installation instructions.

Debian/Ubuntu/etc:

RHEL/CentOS/etc:

Arch/Manjaro/etc:

You can also use your GUI package installation tools to install ExifTool. If the above commands don’t work for you, be sure to leave a comment.

You can download a test PDF: stacer.pdf (which may indicate a future article.)

If you’ve downloaded that file, you need to navigate to the correct directory. Unless you changed something, you likely default to the ~/Downloads directory. You can navigate to that directory with cd ~/Downloads and then use the ls command to ensure the stacer.pdf file exists.

So, the syntax to get started is just this:

In our example, it’d look like this:

You’ll get an output similar to this:

There’s quite a bit of information available and that file doesn’t even have all the information that can be found in your PDF’s metadata.

This PDF isn’t a good one, but you can at least change the title. You can blank the title with this command:

You can blank the title with this command:

Other PDF documents will contain other fields. You can wipe all the fields, resetting the creation and modification times, with this command:

If you’re interested in changing that for privacy reasons, that’s a nice and simple command that will reset all of that metadata. It’s a pretty handy command and ExifTool is a pretty handy tool.

Closure:

So, there’s some ExifTool information and some information about PDF Exif data. That seems like a reasonable article. A new Linux user may be interested in PDF Exif data and this should make it simple enough for anyone to follow along with. You should read the man page because this is an expansive application.

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 site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

Hide The Output From wget

This won’t be a very complicated article and will only apply to those who want to hide the output from wget. It’s just a matter of a simple flag so that it won’t be a very long article.

You can download from the terminal. You can transfer files from the terminal. One of the tools for this is wget. There’s also curl, but this article won’t be complicated and will only apply to those who want to hide the output from wget.

This could probably be called a short, but it’s something I wanted to cover.

wget:

You probably won’t need to install wget. It’s one of those tools that you’ll find installed by default. It’s a pretty handy tool. You can verify that wget is an available application with this command:

The output should match this:

If you want to see why I’d cover such a small piece of wget, check the man page with the following command:

First, you’ll see the description of wget, which is this:

Wget – The non-interactive network downloader.

Now scroll down…

Keep scrolling…

And keep going…

There’s a whole lot to the wget command. It’s a very complicated command. If you’re a new Linux user, you will be overwhelmed by this man page. 

This is the sort of command that you can learn to use bit by bit. You don’t need to learn everything. You almost certainly don’t need everything. That doesn’t mean you can’t use it for useful tasks.

I often use the wget command. I use it not only with my Lubuntu testing but also with my regular activities. I’ll often find the URL for a file and then use wget to download the file. When I do that, it’s because I want to monitor the output.

Other times, I don’t want to monitor the output. So, for that, I use wget in quiet mode. That’s what this article is about.

Hide The Output From wget:

The wget application is an application used in the terminal. I believe there are download managers that are GUIs that use wget in the background. We’ll ignore those and use the terminal. So, press CTRL + ALT + T and let’s learn how to hide the output from wget.

The command you’re after is just the wget command with the -q flag. It would look something like this:

The thing is, this now means that you no longer see the progress. You can tell wget to keep trying until it performs as expected. That’s the ‘complete’ flag ( -c) and looks like this:

You can try this on your own with this command:

That’s a pretty small file, so it won’t take a lot of time. 

You won’t see any messages in your terminal, it will just download the file.

You can test this by running ls in your terminal after the fact. You’ll happily see that you’ve downloaded a file called ‘sort.txt’ and that it kept trying until it was completed.

So, now you know how to hide the output from wget…

Closure:

So, yeah, this probably could have been labeled a ‘short’ article, but I didn’t do so. I try to use that title for things that aren’t as involved, just a simple command in other words. This is pretty simple, but it’s also something you might use regularly.

The wget command is this hulking command with a bunch of options. Not even I fully understand all of the options and I’ve been using the application for years. There’s just a lot to it and that’s far more than we’ll ever cover and far more than most of you will ever use. Still, it can be a pretty handy command and you’ll see more of it in the future.

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 site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

Mastering the Linux Terminal Pipe Command

Well, if it’s not obvious by the title, it soon will be obvious that I’ve once again leaned on AI to write an article, this time about the pipe command. I decided to stick (mostly) to the title AI gave this article, but it was longer than it should be.

AI tried to title this:

“Mastering the Linux Terminal Pipe Command: A Comprehensive Guide”

Anyhow, this is one of those articles that I just can’t write. No matter what I write, it will not be adequate – even though the pipe is a simple enough concept. Much like a recent grep article, this is just one of those articles I won’t write well.

Also, I’m not sure that I should call it a command. It’s more an operator than a command, but the references I see refer to it as a command more frequently than as an operator. Perhaps the word would be ‘operand’? But, for convenience and convention’s sake, I will call it the pipe command.

No, this isn’t something you install. This is a command that you use with other commands. It’s a lot like the operators I’ve already written about. If you’re unfamiliar with the concept, read this article:

How To: Write Text To A File From The Terminal with “>” and “>>”

The short of it is that the pipe takes the output from one command and inserts it into another command. This lets you take the output from one command and parse it with another command. That’s all there is to it – which is why I’m unable to write this article.

Which is why I leaned on my good buddy AI for this article…

Mastering the Linux Terminal Pipe Command:

In the world of Linux, the terminal pipe command stands as a quintessential tool, offering a powerful and flexible means to manipulate data streams. Understanding and mastering the pipe command can significantly enhance your efficiency and productivity in the Linux environment. In this comprehensive guide, we delve into the intricacies of the pipe command, exploring its functionalities, use cases, and advanced techniques.

What is the Pipe Command?

At its core, the pipe command, represented by the symbol |, allows you to redirect the output of one command as input to another command. This seamless connection between commands enables the creation of complex data processing pipelines, facilitating the manipulation and transformation of data with remarkable ease.

Basic Usage:

The basic syntax of the pipe command is straightforward:

Here, the output generated by command1 is passed as input to command2. This chaining of commands enables the execution of multiple operations in a single line, streamlining workflows and reducing the need for intermediate files.

Practical Examples:

Let’s explore some practical examples to illustrate the utility of the pipe command:

Counting Words in a File:

This command displays the number of words in the file file.txt. The cat command outputs the contents of the file, which are then piped to wc -w, which counts the words.

Searching for a Pattern:

Here, grep is used to search for the specified pattern in the file file.txt. The output, which consists of lines containing the pattern, is then piped to wc -l, which counts the number of matching lines.

Sorting Data:

This command sorts the lines in the file file.txt alphabetically and removes duplicate lines using the uniq command.

Advanced Techniques:

While the basic usage of the pipe command is invaluable, mastering advanced techniques can unlock its full potential:

Chaining Multiple Commands:

You can chain multiple commands together to create sophisticated data processing pipelines. Each command in the pipeline operates on the output of the preceding command, enabling complex transformations with minimal effort.

Combining Filters:

Filters such as grep, sed, and awk can be combined to perform intricate text-processing tasks. By leveraging the unique capabilities of each filter, you can manipulate data in a myriad of ways, ranging from pattern matching to text substitution.

Redirecting Output:

In addition to chaining commands, you can redirect the output of a pipeline to a file using the > operator. This allows you to capture the results of your data processing pipeline for future reference or analysis.

Common Pitfalls:

While the pipe command offers immense flexibility, it’s essential to be mindful of potential pitfalls:

  1. Order of Operations:

    The order in which commands are chained together matters. Ensure that you sequence commands appropriately to achieve the desired outcome. A misplaced command in the pipeline can lead to unexpected results or errors.

  2. Input Compatibility:

    Ensure that the output of one command is compatible with the input requirements of the next command in the pipeline. Mismatched data formats or incompatible options can result in errors or unintended behavior.

  3. Performance Considerations:

    Complex pipelines involving multiple commands may incur performance overhead. Be mindful of resource utilization, especially when working with large datasets or computationally intensive operations.

Addendum:

The Linux terminal pipe command is a versatile tool that empowers users to streamline data processing tasks effectively. By mastering its usage and exploring advanced techniques, you can unlock the full potential of the Linux command-line environment. Whether you’re a novice user or a seasoned Linux enthusiast, the pipe command remains an indispensable asset in your toolkit, enabling you to easily conquer complex data manipulation challenges.

Closure:

So, that was AI doing my job for me. Like grep, I tried to write an article about pipe, which was a hot mess. I can usually salvage articles and publish something of my work, but I just didn’t do well with a couple of subjects. This is one of them.

The thing is, I refer to the pipe command with some regularity. I don’t have an article about pipes, so I can’t link to that. This leaves the reader with a search engine and I’d rather they have an excuse to open an additional link. It’s not just good SEO, it’s good hospitality. I’ll never explain everything, but I can explain some things and people won’t need to leave the site to learn those things.

Also, even AI had issues with this article. I told it to write 1200 words and it came up with maybe 600 words. I applaud those who can turn the pipe command into more than a blurb with a few examples that help people grasp the concept. Seriously, hats off to them. I don’t write nearly as well as my volume of articles would imply.

I don’t think I’ll need to use AI for any near-future articles. I’m doing two of them fairly close together because they’re things I feel need to be done. They are articles that need to be written. It is information that needs to be on the site. I did separate the two AI-written articles by some time, just to give folks a break between them. I know, they’re not preferred and they surely don’t match my writing style.

Thanks for indulging me, if nothing else. Amusingly, this isn’t much of a time-saver. The way ChatGPT formats stuff is not compatible with the editor used by my instance of WordPress. I spend a lot of time just formatting things.

Speaking of time invested…

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 site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

Avoid Storing Commonly Used Commands In Your Bash History

This article won’t need to be all that long but it might be complicated as we discuss how to avoid storing commonly used commands in your Bash history. Yes, it’s a long title. 

This is also a bit contrary. It is one of those things that is easier done than said. It’s a very wordy thing, after all. I’ll do my best to describe what’s going on and why you might want to do this.

In this case, Bash stands for Bourne Again Shell. This article only applies to those who are using Bash. Bash is not the only shell available and people may opt to use other shells. If you’re one of those people, I don’t think this is going to work for you.

When you’re using the terminal, you’re using Bash. The commands you enter into the terminal are stored in ~/.bash_history, a hidden file in your home directory. We’ve discussed some of this before.

How To: Have Infinite Bash History
Playing With Your Bash History
How To: Not Save A Command To Bash History
How To: Reload Your .bash_profile

Well, you may type common commands, such as uptime. You may not want to store that command in your Bash history. Do you want to store every time you’ve typed the ls command?

You don’t have to. You have options!

What can you do? Well, you can tell Bash not to store certain commands in the ~/.bash_history file. This is actually a simple operation. To avoid storing commonly used commands in your Bash history, you need only to edit your ~/.bashrc file. I’ll show you how!

Man, this is going to impact the layout…

How To Avoid Storing Commonly Used Commands In Your Bash History:

Yeah, no amount of formatting is going to make that look good.

Anyhow, if this isn’t obvious, you’re going to learn how to do this in the terminal. You could edit your ~/.bashrc file with your favorite GUI editor but we’ll be doing this entire thing in the terminal.

As such, you should have an open terminal. More often than not, you can open your terminal by pressing CTRL + ALT + T. If that doesn’t work, you can find a shortcut to your terminal in your application menu. Should that not work, you’re probably already in the terminal!

So, first, we need to use Nano to edit the ~/.bashrc file. That’s an easy command:

Use your arrow button to navigate to the bottom of that file. Go to the absolute bottom and press enter to start a new line. You can press that button twice to provide some separation and to make it easier to read.

Now, let’s say we don’t want to store the ls, uptime, or touch commands in your Bash history file. We’ll use those as our examples. You should also probably leave a comment in your ~/.bashrc file so that you can easily identify what the code does and remember why you added it. That’s also useful if there are other users.

So, add the following lines:

Next, save that file. As we’re using Nano, you save the file by pressing CTRL + X, then Y, and then ENTER on your keyboard.

Next, you reload your ~/.bashrc file much like you reloaded your Bash profile (which was a link in the intro, should you wish to read it). You reload the ~/.bashrc file with this command:

That should reload the file. If it doesn’t, you can close all your terminal instances and open a new one. If that doesn’t work, you can log out and log back in again.

Anyhow…

Commands starting with :<command>: entries you used will not be stored in the ~/.bash_history file. If you type a command starting with those entries, it will be ignored, meaning they won’t clutter up your ~/.bash_history file with commands you’re already familiar with or commands that don’t need to be stored for things like auditing or security reasons.

It’s pretty simple to do, though it’s a bit of a pain in the butt to explain. This is how you avoid storing commonly used commands in your Bash history – something nobody is going to search for. (If you did find your way here via a search engine, be sure to leave a comment. I want to know who you are!)

Closure:

I realize that this is an awkward article and I’m okay with that. This isn’t something everyone is going to bother with, especially those people who don’t do much in the terminal. Still, it’s possible to avoid storing commonly used commands in your Bash history and now you know how.

Then, someday, someone’s going to search for this exact string of characters and, hopefully, they’ll find this article. I hope this satisfies their curiosity and helps them reach their Linux goals! If you did read this and find it valuable, you can always leave a comment.

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 site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

Create A New User

Today’s article is going to be quick and easy as we simply discuss how you create a new user. This is a fairly basic task and shouldn’t take too long to cover. If you want to create a new user, read on!

If it’s not obvious,  you have a user account. You use this information even if you don’t realize it. Indeed, you use this information when you log into your computer to begin with. When you log in, you’re logging into your user account.

There are other users. You may have a root account or an account for MySQL. If you want to know how many different users are on your system, you can follow along with the following article:

How To: List All Users In Linux

One of the things that helps keep Linux secure is that it’s a true multi-user environment. You can only perform operations on the files you have access to. This is why you use sudo or root.

Managing users is a fundamental task in Linux. This article is going to cover how to create a new user and we’ll be doing so in the terminal. This should be fairly universal and you won’t need to install anything as user management tools will be included by default.

We will use a couple of tools, however. The first among them is:

useradd:

The useradd command is basic and, as the name implies, is used to add new users. There’s nothing complicated about it in today’s article and you can be certain that this is already a tool available to you.

If you’re curious about the command, check the man page:

If you do so, you’ll see that it’s described as this:

useradd – create a new user or update default new user information

So, that’s the correct tool for this job.

passwd:

The other tool we’ll be using is the passwd command. You can again tell by the name what the tool is going to do. Simply, it’s used as a password management tool. This too isn’t all that complicated and you can check the man page with this command:

If you do so, you’ll see that I wasn’t kidding and that this tool does what you think it does. It’s described like so:

passwd – change user password

This is the correct tool for the job. After we create a new user, we’ll assign them a password. If the user wishes, they can change that password on their own.

Create A New User:

As mentioned above, we’ll create a new user with terminal-based tools. This is a nice and universal way to do things. Sure, there are GUI tools out there but this is going to work on any Linux system you’re likely to engage with. You can crack open your favorite terminal, often by just pressing CTRL + ALT + T on your keyboard.

First, we’ll create a new user with the useradd command. The syntax is very simple:

For example:

Now, we’ll add a password. This is also a simple command:

For example:

You’ll be asked to enter the password a couple of times. This is to help ensure that you’ve not made any typographical errors while entering the password. It’s all basic stuff.

Next, you can verify that the new user account has been created. For this next step, we’ll simply use cat and grep.

Again, here’s an example:

The output should look a little something like this:

If you find your user, you’ve done this properly and you’ve learned how to create a new user. I told you that it wouldn’t be too complicated!

Closure:

So… This is an article about how to create a new user. It’s a pretty basic task but one you might just want to know about. You never know when you’ll need to create a new user but now you know where to look if you do need to. User management can be a pretty important task, especially for a server admin.

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 site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

Subscribe To Our Newsletter
Get notified when new articles are published! It's free and I won't send you any spam.
.
Linux Tips
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.