Building from What is the difference between go-Cobra PersistentFlags and Flags?:
Assume we have a top-level prog command, and two start and stop subcommands in it.
Assume the prog command has a persistent flag called database.
How can we make this flag required in the start command only? Note that the stop command should have the flag but it should be optional.
progCmd.MarkPersistentFlagRequired("database") does not work as intended, as it would make the flag required in both start and stop.
startCmd.MarkPersistentFlagRequired("database") does not work either:
no such flag -database