+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'])
+ p = subprocess.Popen(
+ command,
+ shell=True,
+ bufsize=0,
+ stdout=subprocess.PIPE,
+ stderr=subprocess.PIPE,
+ universal_newlines=False,
+ )
+ sel = selectors.DefaultSelector()
+ sel.register(p.stdout, selectors.EVENT_READ)
+ sel.register(p.stderr, selectors.EVENT_READ)
+ stream_ends = 0
+ while stream_ends < 2:
+ for key, _ in sel.select():
+ char = key.fileobj.read(1)
+ if not char:
+ stream_ends += 1
+ continue
+ if key.fileobj is p.stdout:
+ sys.stdout.buffer.write(char)
+ if char in line_enders:
+ sys.stdout.flush()
+ else:
+ sys.stderr.buffer.write(char)
+ if char in line_enders:
+ sys.stderr.flush()
+ p.wait()
+ sys.stdout.flush()
+ sys.stderr.flush()
+ return p.returncode
+
+
+def cmd_with_timeout(command: str, timeout_seconds: Optional[float]) -> int:
+ """Run a command but do not let it run for more than timeout seconds.
+ Doesn't capture or rebroadcast command output. Function returns
+ the exit value of the command or raises a TimeoutExpired exception
+ if the deadline is exceeded.
+
+ >>> cmd_with_timeout('/bin/echo foo', 10.0)
+ 0
+
+ >>> cmd_with_timeout('/bin/sleep 2', 0.1)
+ Traceback (most recent call last):
+ ...
+ subprocess.TimeoutExpired: Command '['/bin/bash', '-c', '/bin/sleep 2']' timed out after 0.1 seconds
+
+ """