rctl extends the process-based limits of rlimit by controlling resource consumption by processes, tasks, and projects defined in the project database.
The rctl mechanism is preferred to the use of rlimit to set resource limits. The only reason to use the rlimit facility is when portability is required across UNIX platforms.
Applications fall into the following broad categories depending on how an application deals with resource controls. Based on the action that is taken, resource controls can be further classified. Most report an error and terminate operation. Other resource controls allow applications to resume operation and adapt to the reduced resource usage. A progressive chain of actions at increasing values can be specified for each resource control.
The list of attributes for a resource control consists of a privilege level, a threshold value, and an action that is taken when the threshold is exceeded.