This function sets the current process group for the process PID. You can use a value of 0 for PID to change the process group of the current process. If both arguments are omitted, defaults to values of 0. Causes a fatal error if the system does not support the function.
Following is the simple syntax for this function −
setpgrp PID, PGRP
This function returns undef on failure and new parent process ID.