operating system services forkpty(creates child process using new pseudo-terminal as the child' controlling terminal returns pair (pidfd)in which pid is in the child and fd is file descriptor of the master end of the pseudo-terminal this function is available only in certain versions of unix kill(pidsigsends the process pid the signal sig list of signal names can be found in the signal module (unixkillpg(pgidsigsends the process group pgid the signal sig list of signal names can be found in the signal module (unixnice(incrementadds an increment to the scheduling priority (the "niceness"of the process returns the new niceness typicallyusers can only decrease the priority of process because increasing the priority requires root access the effect of changing the priority is system-dependentbut decreasing the priority is commonly done to make process run in the background in way such that it doesn' noticeably impact the performance of other processes (unixplock(oplocks program segments into memorypreventing them from being swapped the value of op is an integer that determines which segments are locked the value of op is platform-specific but is typically one of unlockproclocktxtlockor datlock these constants are not defined by python but might be found in the header file this function is not available on all platforms and often can be performed only by process with an effective user id of (root(unixpopen(command [mode [bufsize]]opens pipe to or from command the return value is an open file object connected to the pipewhich can be read or written depending on whether mode is ' (the defaultor 'wbufsize has the same meaning as in the built-in open(function the exit status of the command is returned by the close(method of the returned file objectexcept that when the exit status is zeronone is returned spawnv(modepathargsexecutes the program path in new processpassing the arguments specified in args as command-line parameters args can be list or tuple the first element of args should be the name of the program mode is one of the following constantsconstant description p_wait executes the program and waits for it to terminate returns the program' exit code executes the program and returns the process handle same as p_nowait p_nowait p_nowaito lib fl ff