+logger = logging.getLogger(__file__)
+
+
+def cmd_showing_output(
+ command: str,
+) -> int:
+ """Kick off a child process. Capture and print all output that it
+ produces on stdout and stderr. Wait for the subprocess to exit
+ and return the exit value as the return code of this function.
+
+ """
+ line_enders = set([b'\n', b'\r'])
+ sel = selectors.DefaultSelector()
+ with subprocess.Popen(
+ command,
+ shell=True,
+ bufsize=0,
+ stdout=subprocess.PIPE,
+ stderr=subprocess.PIPE,
+ universal_newlines=False,
+ ) as p:
+ sel.register(p.stdout, selectors.EVENT_READ) # type: ignore
+ sel.register(p.stderr, selectors.EVENT_READ) # type: ignore
+ done = False
+ while not done:
+ for key, _ in sel.select():
+ char = key.fileobj.read(1) # type: ignore
+ if not char:
+ sel.unregister(key.fileobj)
+ if len(sel.get_map()) == 0:
+ sys.stdout.flush()
+ sys.stderr.flush()
+ sel.close()
+ done = True
+ if key.fileobj is p.stdout:
+ # sys.stdout.buffer.write(char)
+ os.write(sys.stdout.fileno(), char)
+ if char in line_enders:
+ sys.stdout.flush()
+ else:
+ # sys.stderr.buffer.write(char)
+ os.write(sys.stderr.fileno(), char)
+ if char in line_enders:
+ sys.stderr.flush()
+ p.wait()
+ return p.returncode