What would the 'at' command be best suited for?

The 'at' command is specifically designed to schedule tasks to be executed at a designated future time. When using the 'at' command, a user can specify a command or script to run once at a specific time in the future, such as "at 14:00" to trigger a task at 2 PM. This feature is particularly useful for one-time operations that need to occur later without requiring terminal interaction at that moment.

In contrast, the other options address functionalities that are not provided by the 'at' command. For instance, running a command periodically is typically managed by the 'cron' job scheduler. Managing running processes deals with various commands, such as 'ps' and 'top', which provide insights into process management. Configuring user permissions involves using commands like 'chmod', 'chown', or modifying configuration files directly, none of which are related to the scheduling of tasks like the 'at' command.