What command would you use to display the contents of a text file?

The command used to display the contents of a text file in Linux is 'cat'. This command stands for "concatenate" and is primarily used to read files sequentially and display their content on the standard output, typically the terminal. When you run 'cat filename.txt', it shows the entire file's content in the terminal window. This functionality makes it a straightforward and widely used tool for quickly viewing the contents of text files.

The other options provided do not fulfill this function: 'show' is not a standard command in Linux for displaying file contents; 'read' is typically associated with reading input from the keyboard or from files in a script; and 'display' is usually related to showing images or graphical files in certain contexts, but not text files.