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…

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Let’s Learn About Grep

I’ve used the grep command many times but haven’t written an article to learn about grep. It seems like a good idea to do so so I can reference this article. That’s something that’s considered a good thing.

The thing is, I’ve tried to write this article before and it just came out terrible. That article never got published. It just wasn’t good enough. As you’ve seen the quality of some of these articles, tells you how bad that attempt went. 

You won’t need to install anything for this article. If you’re using a desktop or a server, you have grep. I’d expect to find grep in embedded systems because it’s just a useful tool. I suppose some companies might have ripped it out of their devices to save space and stop you from rooting around and messing with things.

So, I decided I’d do what I’d done before. I reached out to my buddy ChatGPT and asked them to write an article. Sure enough, ChatGPT did a fine job at it. This doesn’t save me much time. I still need to do all the formatting and that takes more time than you might expect.

So then, let’s get into the article…

About Grep:

The grep command in Linux is a powerful tool used for searching and manipulating text within files or standard input streams. It stands for “global regular expression print” and is primarily used to match patterns in text and display the lines that contain those patterns. grep is highly versatile and widely used in various scenarios, ranging from simple text searches to complex pattern matching and filtering tasks.

Basic Syntax:

The basic syntax for grep is as follows:

  • pattern: The pattern to search for. It can be a simple string or a complex regular expression.
  • file: Optional. The file(s) to search. If not specified, grep reads from standard input.
Common Options:
  • -i or --ignore-case: Ignore case distinctions.
  • -v or --invert-match: Invert the sense of matching, displaying non-matching lines.
  • -r or --recursive: Recursively search subdirectories.
  • -n or --line-number: Prefix each line of output with its line number.
  • -l or --files-with-matches: Display only the names of files containing matches.
  • -E or --extended-regexp: Interpret pattern as an extended regular expression (ERE).
  • -F or --fixed-strings: Interpret pattern as a list of fixed strings (not regular expressions).
Examples:

Basic Text Search:

This command searches for the occurrence of “keyword” in the file file.txt and displays all lines containing that keyword.

Case Insensitive Search:

This command performs a case-insensitive search for the pattern “pattern” in the file file.txt.

Invert Match:

This command displays all lines in file.txt that do not contain the word “exclude”.

Search in Multiple Files:

This command searches for the pattern in both file1.txt and file2.txt.

Recursive Search:

This command recursively searches for the pattern in all files within the specified directory and its subdirectories.

Display Line Numbers:

This command displays the line numbers along with the lines containing the pattern in file.txt.

Regular Expressions:

grep supports regular expressions, allowing for more advanced pattern matching. Regular expressions enable users to define complex search patterns, such as matching specific character sequences, ranges, or repetitions.

For example:

  • . matches any single character.
  • ^ matches the beginning of a line.
  • $ matches the end of a line.
  • [ ] specifies a character class.
  • * matches zero or more occurrences of the preceding element.
  • \ is used to escape special characters.
Additional Information:

The grep command is an essential tool for text processing and manipulation in the Linux terminal. Its versatility, combined with regular expressions, allows users to perform a wide range of tasks, including simple text searches, pattern matching, filtering, and data extraction. Whether it’s analyzing log files, searching for specific information in codebases, or performing system administration tasks, grep remains an indispensable utility for Linux users. Understanding its capabilities and various options can greatly enhance productivity and efficiency when working with text data in the terminal.

Closure:

So, there you have it. You have an AI-generated article about grep. It’s formatted quite differently than I’d normally format it, but it works. I dare say that AI did the job better than I had when I tried in the past.

People worry about AI but it’s just a tool. I am slowly learning when to make it useful to me. I’m not sure how many jobs AI is going to replace, but I can see lots of ways to use AI to make life easier. I can see ways to make AI more educational, such as in this article. It’s a nice overview, I think.

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How To: Crack A PDF Password

I don’t know how handy today’s article is going to be in reality but it’s sort of possible to crack a PDF password. Once you read the article, you’ll see why I said “sort of possible”. The odds of success will vary greatly.

Everybody knows what a PDF file is. It’s a Portable Document Format. This is actually a standard (ISO 32000). You don’t need Adobe products to create, edit, or read PDF-formatted documents. Odds are good that your distro comes with tools for manipulating PDF documents.

It’s possible to password-protect a PDF document. You can have an owner’s password (allowing editing) or you can have a user’s password (allowing you to read the document). This may be something you’ve encountered in the past.

Well, like all things password-protected, it’s possible to crack the password.

What do I mean by crack? I mean it will reveal the password to you in plain text. This will allow you to access the document in one form or another, depending on which password you crack.

This is gonna take some time…

Also, I’ll assume you’re using something based on Debian because I’ve not tested this with other distros. I’ve only tested this on my systems.

The tool we’ll be using is a ‘brute-force’ password cracker. That means it starts from the letter a and works its way up, adding new letters after the rest of the letters have been tried. So, you’ll see aa, ab, ac, ad, and progression along those lines. You can immediately see why this is going to take a while.

The tool we’ll be using is helpfully called ‘pdfcrack’.

pdfcrack:

This pdfcrack is a terminal-based PDF password-cracking tool. You can use brute force or lists of words such as common passwords. You can also specify the character list, though the default is to just use the regular alphabet in both uppercase and lowercase formats.

The pdfcrack application is helpfully described as such:

pdfcrack – Password recovery tool for PDF-files

I’ll assume that you’re only trying to recover passwords on documents you should legally have access to. I assume that you won’t use this to access content that does not belong to you. That seems like a safe assumption!

As you can see, this is the correct tool if you want to crack a PDF password.

Crack A PDF Password:

As mentioned above, you’ll crack passwords in the terminal. That requires an open terminal, so we might as well install pdfcrack in the terminal. Just press CTRL + ALT + T and that will usually open up a terminal for you.

With your terminal now open, install pdfcrack:

With that installed, check the man page:

Download:

Example PDF File

Now, crack it…

As it’s a download, it’s probably in your ~/Downloads directory, but mine is stored in my ~/Documents directory because it’s a document. So, my example:

That uses a very simple password that should be cracked in a few seconds. On my older and slower computer, I was able to do more than 20,000 words per second. This short password should crack almost instantly.

Leave a comment telling me what the password is!

By default, pdfcrack will crack the user password. You can specify which password you wish to crack. Though the syntax is a little wonky. In this case, the syntax is as follows:

Which translates into the following…

For the owner:

For the user:

If you want to pause this, you can! 

To pause a running pdfcrack instance just press CTRL + C. This will save the progress as savedstate.sav. The program will automatically resume when you run the command again. Pretty neat!

There’s a lot you can do with this command. Let’s say you recall the password was between 8 and 12 characters and want to just search in that area.

You can also specify the character set. If you want to use uppercase, lowercase, and numbers you can do that. You just add them to the command with the -c flag, making sure to put them in quotes. That’d look like this:

You can specify a wordlist like so:

The format for that file appears to require one word per line and there are collections of common passwords you can download to help you crack a PDF password.

As you can imagine, and as you were warned near the start, this process can take a while. Assuming you have the right characters loaded and enough time, it’s certain to work eventually.

Go ahead and crack my example file above. That one won’t take you very long, even on a slow computer. It won’t be instantaneous, but it’ll be pretty quick.

If you want, you can also run a benchmark to see how fast your computer is. The command to do that is quite simply this:

I ran this on the slowest computer I use. I didn’t run it on anything faster because I don’t care that much. I’m sure you’ll do better on your computers, though you can share the results as a way to compare your rig with others.

Anyhow, my output was this:

Be sure to check out the man page. It’s a simple application but there are many options available for pdfcrack and you might as well learn about them now. You never know when you’ll find an old PDF document with a forgotten password. It can (and does) happen!

Also, be sure to check the pdfcrack project page.

Closure:

So, you might wonder why I’d include an article like this. After all, isn’t cracking passwords a potential legal mess? Isn’t it immoral to crack passwords? Is it even legal to crack passwords?

The answer is simple enough. It’s a tool you can use to recover your lost passwords. You can use this tool to access things that you shouldn’t be accessing, just like you can use a screwdriver to poke things you shouldn’t be poking. I’m just giving information.

I am also not a lawyer. I permit you to crack the password of the included file. For other files, don’t do anything illegal in your jurisdiction. If it’s a crime, don’t do it. I’m decidedly not your lawyer. If you think this requires asking a lawyer, go ahead and do so.

That and it’s not a great secret. If you’re relying on a password to protect PDF files from anyone serious, you’re probably doing your security wrong. It’s well known that this is possible and that the tools are easily installed. PDF passwords aren’t very good for security, though you can make complicated passwords.

The distro you’re using may very well have pdfcrack available, even if it isn’t one of the Debian-based distros. Just search and you can find it. With some work, you can even mostly install it with PIP. Just click the link above to the project page for more information about that.

As always…

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The du Command In Linux

There’s always time for a basic article or two and today we’ll do that as we just play around with the du command in Linux. This is a functional tool and one you can learn to use in just a few minutes. Because of that, I’ll try to keep the article reasonably short.

Storage…

On Linux, everything is a file. These files are stored with a system – such as a particular formatting method like Ext4. Collectively, this is your file system.

Because of this, you may have done similar things, you’ll find that file sizes are all divisible by four. That’s because of the way things are stored. They’re stored in blocks and 4KB is (generally speaking) the smallest block you can have. So, it only makes sense that things can be divided by four.

Running out of storage space is A BAD THING®. It can even prevent you from booting! You do not want to run out of space on your drives. You don’t want to run out of space on any of your partitions.

When you installed Linux, you should have taken care to ensure that the partitions will be large enough for you to grow into. It’s possible to add storage. You can even modify your system to move your ~/home directory onto a partition all its own.

It’s easier to ensure you have enough room when you start. Storage space is relatively inexpensive these days. You can get really fast storage (such as an NVMe M.2 SSD) for little money. If your motherboard doesn’t support NVMe, you can get a cheap PCIe riser card to add that feature.

We’ll be using the du command to see how much space you’ve used.

The du Command:

The du command is a terminal-based application. You shouldn’t need to install anything for this article, it should be installed by default. We’ve previously used this command to sort files by size if you’re curious.

Anyhow, you can ensure du is available with the following terminal command:

Which should give you an output like this:

If you get an output similar to that, you’re good to go and won’t need to install anything to finish this article. The man page can be accessed with the following terminal command:

The output from that command should be a good indicator that we’re using one of the correct tools for the job. This being Linux, there are many choices. In this case, the du command is described as:

As you can tell by the introductory paragraphs, that’s a good tool for the task we’ve set for ourselves today. We want to see how much file space we’re using.

Using The du Command In Linux:

If you read the above paragraphs you’d know that this is another one of those things you do in the Linux terminal. Yes, there are graphical tools that will let you do this – but this way is universal. You’re going to find the du command on any Linux system you’re likely to touch. So, press CTRL + ALT + T and we can get going.

With your terminal open, you can just start with the basics:

That will show you the bytes used by the directories. We want to see the storage space consumed by directories and files, so we’ll add the -a flag to the following command:

That should show file and directory sizes in bytes. That’s not very readable by a human unless you want to do some math in your head. So instead we’re going to add the -h flag. Like so:

That’s all well and good. You can use cd to navigate around your computer or you can specify the path. How do you do that? Well, the syntax follows:

So, if we want to view the storage consumption of the ~/Downloads directory we’d simply use the following command:

Now, if you just want to see the total value of the directory you can use the following command with the -s flag:

If you want to find out how much storage space is consumed by your entire ~/home/<user> directory, that’s a very simple command:

I’d not suggest using the du command to check the entire drive of a running system. It will want to also calculate anything plugged into the computer and take forever. There are other ways to view drive usage information.

If you want to use a GUI, here’s a few tools for you:

A Few Ways To Visualize Disk Usage In Linux

There are innumerable ways to do this in the terminal and I’ve covered many of them. Most recently, I showed you a way to use Python to view disk usage. I admit my bias, but that’s a neat way to give you some basic information in a handy format that’s easily understood.

This is one of those things you can do with a multitude of tools. It is also a fairly basic task and something we should all be aware of. Know how much free storage you have and act accordingly.

Don’t wait for the drives to fill up before acting because that just makes it harder on you. You know the adage about how an ounce of prevention is better than a pound of cure? Well, keep that in mind when you think about your storage solutions.

Closure:

Oh, I’m sure I’ve mentioned the du command before. It sounds like something I’ve written about. I do know that I used it so that you could sort files by size, which is nice. At least I’m pretty sure I did…

At this point, who knows? I could do a lot of searching just to check, but the search doesn’t always do a good job and it’s too late now because I’ve written the article!

As of today, you should be fairly fluent in the du command. You might want to read the man page. There’s quite a bit that I didn’t cover. I only covered the basics. More specifically, I only covered the ways I use the du command. You may have very different needs. You may have a very different process. With that in mind, read the man page.

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Mastering Efficiency: Unleashing the Power of Bash Aliases

In the realm of command-line prowess, efficiency is king, such as Bash aliases. Every keystroke saved is a victory, and every shortcut mastered is a step toward domination over the terminal.

Among the arsenal of tools at your disposal, one weapon stands out as a champion of efficiency: Bash aliases. These humble shortcuts can transform your command-line experience from mundane to magnificent, allowing you to wield the power of complex commands with the simplicity of a single word.

Join us on a journey as we delve into the world of Bash aliases and unlock their full potential.

What are Bash Aliases?

Bash aliases are custom shortcuts or abbreviations that you can create to simplify and speed up your command-line tasks. They allow you to define your own commands or override existing ones with your preferred options or parameters.

Think of them as your personal command-line assistant, ready to execute your commands at a moment’s notice.

Why Use Bash Aliases?

The benefits of Bash aliases are manifold:

  1. Speed: With aliases, you can execute complex commands with just a few keystrokes, saving valuable time and effort.

  2. Simplicity: Long and convoluted commands can be distilled into concise aliases, making your command-line interactions more intuitive and less error-prone.

  3. Customization: Aliases are highly customizable, allowing you to tailor your command-line environment to suit your specific needs and preferences.

  4. Productivity: By automating repetitive tasks, aliases can significantly boost your productivity and streamline your workflow.

How to Create Bash Aliases

Creating Bash aliases is a breeze. Open your .bashrc  file, located in your home directory, using your favorite text editor (such as Nano). Then, add your alias definitions to the file using the following syntax:

Replace shortcut with the alias you want to create and command with the command you want to associate with the alias. For example:

This alias allows you to list all files in the current directory in a long listing format with file details.

Once you’ve added your aliases, save the .bashrc file and either restart your terminal or run source ~/.bashrc to apply the changes.

Examples of Useful Bash Aliases

Here are some examples of useful Bash aliases to get you started:

Best Practices for Bash Aliases

To make the most of Bash aliases, keep the following best practices in mind:

  1. Choose meaningful names: Use descriptive names for your aliases to make them easy to remember and understand.

  2. Avoid overriding existing commands: Be cautious when overriding existing commands with aliases to prevent confusion and unintended consequences.

  3. Document your aliases: Consider adding comments to your .bashrc  file to document your aliases and their purposes for future reference.

  4. Stay organized: Group related aliases together and organize them logically within your .bashrc  file for easier management.

Conclusion

In the fast-paced world of the command line, efficiency reigns supreme. Bash aliases empower you to wield the full power of the terminal with unparalleled speed and simplicity.

By mastering the art of aliases, you can elevate your command-line prowess to new heights and easily conquer even the most daunting tasks. So go forth, fellow command-line warriors, and unleash the power of Bash aliases upon the digital realm!

Can you tell that this was written by AI? The prompt I used for this was:

Write an article about Bash Aliases in the style of linux-tips.us.

It didn’t do very well at nailing my style and it used a lot of headers. It also rambled on quite a bit, but I do that too. I’m not sure how much time this saved. I still had to do quite a bit of formatting. A simple cut-and-paste would not match the mostly consistent formatting I have used as of late. That meant quite a bit of formatting.

I also ran the article through Grammarly. It’s too bad that they won’t accept me into the affiliate program. I quite like what they do for my writing. They make me look almost literate!

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.

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