SWI-Prolog -- process

Availability::- use_module(library(process)).(can be autoloaded)

True if PID completed with Status. This call normally blocks until the process is finished. Options:

timeout(+Timeout): Default: infinite. If this option is a number, the waits for a maximum of Timeout seconds and unifies Status with timeout if the process does not terminate within Timeout. In this case PID is not invalidated. On Unix systems only timeout 0 and infinite are supported. A 0-value can be used to poll the status of the process.
release(+Bool): Do/do not release the process. We do not support this flag and a domain_error is raised if release(false) is provided.

Status is one of exit(Code) or killed(Signal), where Code and Signal are integers.