cat is one of the first commands that a command-line warrior must learn. It is usually used to read, display, or concatenate the contents of a file, but cat is capable of more than just that. We even scratch our heads when we need to combine standard input data, as well as data from a file using a single-line command. The regular way of combining the stdin data, as well as file data, is to redirect stdin to a file and then append two files. But we can use the cat command to do it easily in a single invocation. In this recipe we will see basic and advanced usages of cat.
The cat command is a very simple and frequently used command and it stands for concatenate.
The general syntax of cat for reading contents is:
$ cat file1 file2 file3 ...
This command concatenates data from the files specified as command-line arguments.
To print contents of a single file:
$ cat file.txt This is a line inside file.txt This is the second line inside file.txt
To print contents...