Linux Commands: Cat

A Comprehensive Guide to the Cat Command for Adding Content to Files

When it comes to file manipulation, the cat command is a powerful tool similar to tail in some ways. However, what sets cat apart is its ability to not only display file content but also add content to a file.

To begin with, let’s explore the basic usage of cat. The command cat file simply prints the content of a file to the standard output.

You can also use cat to print the content of multiple files by specifying them all together: cat file1 file2.

If you want to combine the content of multiple files into a new file, you can use the > operator for redirection: cat file1 file2 > file3. This will create a new file (file3) and concatenate the content of file1 and file2 within it.

To append the content of multiple files to an existing file, you can utilize the >> operator: cat file1 file2 >> file3. This will add the content of file1 and file2 at the end of file3. If file3 doesn’t exist, it will be created.

One useful feature of cat is its ability to display line numbers. By using the -n option (cat -n file1), you can view the content of file1 along with line numbers. If you only want to add line numbers to non-blank lines, you can use the -b option. Additionally, the -s option removes multiple empty lines from the output.

Another way to utilize cat is by combining it with the pipe operator | to pass the content of a file as input to another command. For example: cat file1 | anothercommand.

It’s important to note that the cat command works not only on Linux but also on macOS, Windows Subsystem for Linux (WSL), and any UNIX environment.

Tags: Linux commands, cat command, file manipulation, command line, UNIX environment