Linux for Beginners: The Less Command

If you are new to Linux, you might have heard of the less command, but what does it do and how can you use it effectively? In this blog post, we will explain what the less command is, how to use it, and how it compares to the cat command. We will also share some best practices and tips on using the less command flags. By the end of this post, you will have a better understanding of the less command and how it can help you work with files in Linux.

What is the Less Command?

The less command is a Linux command line utility that allows you to view the contents of a file or the output of another command without loading the entire file into memory. This makes it faster and more efficient than other commands that display the whole file at once, such as cat or more. The less command also gives you more control over how you view the file, as you can scroll up and down, search for keywords, jump to specific lines, and more.

The less command is named after the more command, which is similar but has fewer features. The name is a pun on the phrase “less is more”, meaning that sometimes having less functionality is better than having more. The less command is also sometimes called the opposite of more, as it allows you to do more with less.

How to Use the Less Command

To use the less command, you simply type less followed by the name of the file you want to view, or the command whose output you want to pipe to less. For example, if you want to view the file example.txt, you can type:

less example.txt

If you want to view the output of the ls command, which lists the files and directories in the current directory, you can type:

ls | less

The pipe symbol (|) means that the output of the first command is passed as the input to the second command.

When you use the less command, you will see the first part of the file or the output on your screen, with a colon (:) at the bottom indicating that you can enter commands to navigate or manipulate the text. Here are some of the most common commands you can use with less:

• To scroll down one line, press the down arrow key or j.
• To scroll up one line, press the up arrow key or k.
• To scroll down one page, press the space bar or f.
• To scroll up one page, press b.
• To go to the end of the file or the output, press G.
• To go to the beginning of the file or the output, press g.
• To search for a keyword, type / followed by the keyword and press enter. To go to the next occurrence of the keyword, press n. To go to the previous occurrence of the keyword, press N.
• To jump to a specific line number, type the line number followed by G. For example, to go to line 42, type 42G.
• To quit the less command, press q.

You can also use the arrow keys, the page up and page down keys, and the home and end keys to navigate the file or the output.

The Less Command vs the Cat Command

The cat command is another Linux command line utility that displays the contents of a file or the output of another command. However, unlike the less command, the cat command does not allow you to scroll or search the text, and it loads the entire file or output into memory. This means that the cat command is faster and simpler than the less command, but it also has some drawbacks.

The main drawback of the cat command is that it can be overwhelming and impractical to use when the file or the output is very large or contains a lot of information. For example, if you use the cat command to view a log file that has thousands of lines, you will see the whole file on your screen at once, and you will have to scroll up and down manually to find what you are looking for. This can be very time-consuming and frustrating, especially if you are looking for a specific keyword or line number.

The less command, on the other hand, allows you to view the file or the output in chunks, and gives you more options to navigate and search the text. This makes it easier and more convenient to use when the file or the output is large or complex. For example, if you use the less command to view the same log file, you will see only the first part of the file on your screen, and you can use the commands we mentioned above to scroll, search, or jump to the part you are interested in. This can save you a lot of time and effort, and make your work more efficient.

Another drawback of the cat command is that it can cause problems when the file or the output contains special characters or binary data that are not meant to be displayed on the screen. For example, if you use the cat command to view an image file, you will see a lot of gibberish and noise on your screen, and you might even mess up your terminal settings. The less command, on the other hand, can detect when the file or the output is not text, and display a message saying “may be binary” or “may contain binary data”. This can prevent you from accidentally viewing something that is not meant to be viewed with the cat command.

Therefore, the less command is more versatile and powerful than the cat command, and it is recommended to use it when you want to view files or outputs that are large, complex, or contain non-text data. The cat command is still useful when you want to view files or outputs that are small, simple, or contain only text data, or when you want to concatenate or redirect files or outputs to other commands.

Best Practices for Using the Less Command Flags

The less command also has a number of flags or options that you can use to modify its behavior or functionality. For example, you can use the -N flag to display line numbers, the -S flag to chop long lines instead of wrapping them, or the -i flag to ignore case when searching. You can see the full list of flags and their descriptions by typing man less or less --help.

However, not all flags are equally useful or appropriate for every situation. Some flags can make the less command more efficient or convenient, while others can make it more confusing or complicated. Therefore, it is important to use the flags wisely and follow some best practices when using them. Here are some of the best practices for using the less command flags:

• Use only the flags that you need or want. Do not use flags that you do not understand or that do not serve your purpose. For example, if you do not need to see line numbers, do not use the -N flag. If you do not want to chop long lines, do not use the -S flag. Using unnecessary flags can clutter your screen and make the less command harder to use.
• Use the flags in the right order. The order of the flags can affect how the less command works. For example, if you use the -S flag before the -N flag, the line numbers will be chopped along with the long lines. If you use the -N flag before the -S flag, the line numbers will be displayed separately from the chopped lines. Therefore, you should use the flags in the order that makes sense for your goal. For example, if you want to see line numbers and chop long lines, you should use the -N flag before the -S flag.
• Use the flags consistently. If you use different flags for different files or outputs, you might get confused or make mistakes. For example, if you use the -i flag to ignore case when searching for one file, but not for another file, you might miss some matches or get false positives. Therefore, you should use the same flags for the same types of files or outputs, unless you have a good reason to change them. This can make your work more consistent and reliable.

Conclusion

The less command is a Linux command line utility that allows you to view the contents of a file or the output of another command without loading the entire file into memory. It also gives you more control over how you view the file, as you can scroll, search, jump, and more. The less command is more versatile and powerful than the cat command, which displays the whole file or output at once and does not allow you to navigate or search the text. The less command also has a number of flags or options that you can use to modify its behavior or functionality, but you should use them wisely and follow some best practices when using them. By using the less command effectively, you can make your work with files in Linux easier and more efficient.

We hope this blog post has helped you understand the less command and how to use it in Linux for beginners. If you have any questions or feedback, please leave a comment below. Thank you for reading!