run_tee.py

# known-good: python 3.7.0

class RunOutput(object):
   def __init__(self, return_code, stdout, stderr):
      self.return_code = return_code
      self.stdout = stdout
      self.stderr = stderr

def run_tee(s):
   """Runs shell command s, returning a RunOutput with (return_code, stdout, stderr).

      Returns stdout and stderr as unicode strings trimmed of whitespace at ends.

      Also, transparently passes through stdout and stderr unaltered, like tee."""
   import subprocess, select
   print("\nrun_tee:\n about to call command: {}\n".format(s))
   process = subprocess.Popen(s, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)
   sout_fd = process.stdout.fileno()
   serr_fd = process.stderr.fileno()
   so = b''
   se = b''
   while process.poll() is None:
      fds, _, _ = select.select([sout_fd, serr_fd], [], [], .1)
      if sout_fd in fds:
         new_so = process.stdout.readline()
         sys.stdout.buffer.write(new_so)
         sys.stdout.buffer.flush()
         so += new_so
      if serr_fd in fds:
         new_se = process.stderr.readline()
         sys.stderr.buffer.write(new_se)
         sys.stderr.buffer.flush()
         se += new_se
   new_so = process.stdout.read()
   sys.stdout.buffer.write(new_so)
   sys.stdout.buffer.flush()
   so += new_so
   new_se = process.stderr.read()
   sys.stderr.buffer.write(new_se)
   sys.stderr.buffer.flush()
   se += new_se
   rc = process.returncode
   r = RunOutput(rc, so.decode().strip(), se.decode().strip())
   print("\nrun_tee:\n finished calling command: {}\n return_code: {}\n".format(s,r.return_code))
   return r