What does the command 'echo $?' display?

• A. The exit status code of the last executed command.
• B. The process ID of the current shell.
• C. The current user's ID.
• D. The number of commands executed.

Answer: (A)

The thing being tested is how the shell reports the completion status of the command that just ran. The special parameter $? holds that exit status. When you run a command, it returns an exit code: 0 means success, and any nonzero value indicates an error or some condition. Echoing $? prints that numeric code, letting you quickly see whether the previous command succeeded.

For example, running a successful command like true and then echoing $? will show 0. Running a failing command like false and then echoing $? will show 1. If a command fails in a way that returns a different nonzero code, that exact number will appear. Remember, $? reflects only the most recently executed foreground command, and it gets overwritten by the next command’s exit status.