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How to Use the Linux cat Command – A Beginner’s Guide

Linux cat Command in Monitor

New to Linux and wondering how to use the cat command? Look no further! In this beginner's guide, we'll explore what the cat command does, how it works, and some examples of how to use it.

What is the cat command?


The cat command is short for "concatenate," and it is used to display the contents of files on the terminal. The command can also be used to create new files, append to existing files, or even combine multiple files into a single file.


Syntax


The basic syntax of the cat command is:


cat [OPTION]... [FILE]...


In this syntax, the options are optional and can be used to modify the behavior of the command. The files are the names of the files that you want to display or concatenate.

Using the cat command to display file contents.


The most common use of the cat command is to display the contents of a file on the terminal. To do this, simply type "cat" followed by the name of the file. For example, to display the contents of a file called "test6.txt," type:


cat test6.txt


This will display the contents of the file on the terminal. If the file is too long, you can use the "less" command to display the contents one page at a time:

cat test6.txt | less

Linux cat Command Show File Contents

Using the cat command to create new files.


The cat command can also be used to create new files. To do this, type "cat" followed by a greater than sign (>) and the name of the new file. For example, to create a new file called "newfile.txt," type:


cat > newfile.txt


Once you have typed this command, you can start typing the contents of the file. When you are finished, press "Ctrl+D" to save the file and exit.


Using the cat command to append to files.


The cat command can also be used to append to existing files. To do this, type "cat" followed by two greater than signs (>>) and the name of the file. For example, to append to a file called "existingfile.txt," type:


cat >> existingfile.txt


Once you have typed this command, you can start typing the contents that you want to append to the file. When you are finished, press "Ctrl+D" to save the changes and exit.


Using the cat command to combine multiple files.


Finally, the cat command can be used to combine multiple files into a single file. To do this, type "cat" followed by the names of the files that you want to combine and the name of the new file. For example, to combine three files called "file1.txt," "file2.txt," and "file3.txt" into a new file called "combinedfile.txt," type:


cat file1.txt file2.txt file3.txt > combinedfile.txt


This will create a new file called "combinedfile.txt" that contains the contents of all three files.

Options

The Linux cat command comes with various options that can modify its behavior. Here are some of the commonly used options:

  • -n or --number: This option displays line numbers for each line in the output.
  • -b or --number-nonblank: This option displays line numbers for non-blank lines only.
  • -s or --squeeze-blank: This option suppresses repeated empty lines in the output.
  • -E or --show-ends: This option displays a dollar sign ($) at the end of each line in the output.
  • -T or --show-tabs: This option displays tab characters as ^I in the output.
  • -v or --show-nonprinting: This option displays non-printable characters in the output as ^ and the corresponding character.
  • -u or --unbuffered: This option disables output buffering, which can be useful when redirecting output to another command or file.

These options can be used in various combinations to modify the behavior of the cat command according to your specific needs. To see a full list of options and their descriptions, you can refer to the cat command's manual page by typing "man cat" in the terminal.

Conclusion


The cat command is a powerful and versatile tool that every Linux user should know how to use. By understanding its basic syntax and common use cases, you can easily display file contents, create new files, append to existing files, and even combine multiple files into a single file. With this beginner's guide, you are now ready to start using the cat command with confidence!