Question

Which one of the following commands is incorrect?

(a) cat  file01

(b) cat > file01

(c) cat >> file1

(d) cat  -a file01

The question was asked in final exam.

This intriguing question originated from Displaying and Creating Files: cat Command topic in portion Handling Ordinary Files of Unix

Answer 1

The correct answer is:

(d) cat -a file01

Explanation:

• (a) cat file01: This command displays the contents of file01 on the terminal. It is a valid command.
• (b) cat > file01: This command allows you to create or overwrite the content of file01. After running the command, you can type text, and pressing Ctrl+D will save the content to the file. It is a valid command.
• (c) cat >> file1: This command appends the contents of the file to file1. It is also a valid command.
• (d) cat -a file01: This command is incorrect because the cat command does not have an -a option. There is no -a option for cat. Therefore, this command will result in an error.

Thus, (d) cat -a file01 is the incorrect command.