How To Use cat Command In Linux / UNIX

The cat command in Linux and Unix is used to concatenate and display files. It reads files sequentially, writing their contents to the standard output.

Here are some examples of how to use the cat command:

• To display the contents of a file, use the following syntax:

cat file

Replace file with the name of the file that you want to display.

• To display the contents of multiple files, specify the names of the files as arguments to the cat command. For example:

cat file1 file2 file3

This will display the contents of file1, file2, and file3 in the order specified.

• To concatenate the contents of multiple files and save the result to a new file, use the cat command with the > operator and the name of the new file. For example:

cat file1 file2 file3 > newfile

This will concatenate the contents of file1, file2, and file3 and save the result to a new file called newfile.

• To append the contents of one file to another file, use the cat command with the >> operator and the name of the file to which you want to append the contents. For example:

cat file1 >> file2

This will append the contents of file1 to the end of file2.

• To display the contents of a file and also display line numbers, use the -n option. For example:

cat -n file

This will display the contents of file with line numbers.

Note: The cat command is a simple but powerful tool that is commonly used in scripts and on the command line to manipulate and display text files. It has many other options and features that allow you to customize its behavior, such as the ability to display non-printing characters, display the ends of lines, and more. Consult the cat man page or online documentation for a complete list of options and usage examples.