How to determine the exit code of a running command in Linux?

In Linux, the exit code of the last executed command is stored in a special environment variable $?.

To find out the exit code, simply execute after the command:

echo $?

A code of 0 usually indicates successful execution, while any other value signifies an error or a special condition.

Example:

ls /nonexistent
echo $?  # Will output the error code, for example 2

This allows scripts and users to check the result of command execution.