GNU R execute and control system processes

 Tools to run system processes in the background.
 It can check if a background process is running; wait on a background
 process to finish; get the exit status of finished processes; kill
 background processes and their children; restart processes. It can read
 the standard output and error of the processes, using non-blocking
 connections. 'processx' can poll a process for standard output or
 error, with a timeout. It can also poll several processes at once.