On UNIX, returns the process ID as a decimal string. On Windows, returns the result of GetProcessId() also as a string. If the subprocess has terminated, this will return %NULL.
the subprocess identifier, or %NULL if the subprocess has terminated
2.40
See Implementation
On UNIX, returns the process ID as a decimal string. On Windows, returns the result of GetProcessId() also as a string. If the subprocess has terminated, this will return %NULL.