Which command displays text to standard output (STDOUT)?

The command that displays text to standard output (STDOUT) is "echo". This command is commonly used in shell scripting and in command-line interfaces to produce a string or a variable's value as output to the terminal. When you type "echo" followed by a string, such as "Hello, World!", it outputs that string directly to the screen, making it a straightforward way to display messages or variable contents.

When working with scripts or when needing to provide feedback to users, using "echo" is simple and effective. It also supports options that allow for more advanced usage, such as controlling whether to interpret escape characters or to add a new line at the end of output.

The other options do not consistently serve this primary purpose. "print" is not a standard command in the Linux shell; it may be used in programming languages but is not applicable here. "display" is more associated with image viewing commands, particularly in graphical contexts. The "cat" command can also display text files by concatenating and displaying their contents, but it is primarily used for reading files rather than displaying arbitrary strings directly. Thus, while "cat" can output text, it does not align with the general use case of displaying text directly as "echo" does