rc-service:tldr:64d02

The given command sudo rc-service --dry-run ${service_name} ${command_name} is a command-line instruction to interact with the rc-service command in Unix-like operating systems.

Here is an explanation of each component of the command:

1. sudo: It is a command used in Unix-like systems to run subsequent commands with elevated privileges. sudo stands for "Super User Do," and using this command usually requires authentication, such as providing the system password.

2. rc-service: It is a command used in Gentoo Linux and some other related distributions to control services on the system. It allows starting, stopping, restarting, or checking status of services.

3. --dry-run: It is an option specific to the rc-service command. When used, it doesn't perform the actual actions but simulates them. It is helpful to check the expected outcome or verify the correct execution of a command without making any changes to the system.

4. ${service_name}: It is a placeholder representing the name of the service to be acted upon. You need to replace ${service_name} with the actual name of the service you want to target. For example, if you want to check the dry run of the service called nginx, you would replace ${service_name} with nginx.

5. ${command_name}: It is another placeholder representing the specific action to be performed on the service. You need to substitute ${command_name} with the desired action, such as start, stop, restart, status, etc. The available actions depend on the service management implementation for your distribution.