How to use the "hold" file feature to delay backups when circumstances warrant

Scenario:
You have two Amanda configurations "DailySet1" and "MonthlySet1". In this case you have two configurations
that are using the same tape drive. The question is how do you create a safeguard to prevent both
configuration from running in conflict with each other and trying to access the same drive at the same time.

Solution:
If the file /etc/amanda/config/hold exists, amdump will wait until it is removed before starting the backups.
This allows scheduled backups to be delayed when circumstances warrant, for example, if the tape device is
being used for some other purpose. While waiting, amdump checks for the hold file every minute.

Example:
You are running a full monthly backup "MonthlySet1" that is taking more then 12 hours because of its size.
How do you prevent the "DailySet1" backup that runs every day from starting while "MonthlySet1" is still running?

When creating a crontab for the monthly backup configuration use this syntax:

touch /etc/amanda/DailySet1/hold && amdump MonthlySet1 && rm /etc/amanda/DailySet1/hold