python - Popen.communicate() throws UnicodeDecodeError -

i have code:

def __executecommand(self, command: str, input: str = none) -> str:     p = sub.popen(command, stdout=sub.pipe, stderr=sub.pipe, stdin=sub.pipe, universal_newlines=true)     p.stdin.write(input)     output, error = p.communicate()     if (len(errors) > 0):         raise environmenterror("could not generate key: " + error)     elif (p.returncode != 0):         raise environmenterror("could not generate key. return value: " + p.returncode)     return output 

and unicodedecodeerror in line output, error = p.communicate():

traceback (most recent call last):   file "c:\python34\lib\threading.py", line 921, in _bootstrap_inner     self.run()   file "c:\python34\lib\threading.py", line 869, in run     self._target(*self._args, **self._kwargs)   file "c:\python34\lib\subprocess.py", line 1170, in _readerthread     buffer.append(fh.read())   file "c:\python34\lib\encodings\cp1252.py", line 23, in decode     return codecs.charmap_decode(input,self.errors,decoding_table)[0] unicodedecodeerror: 'charmap' codec can't decode byte 0x81 in position 27: character maps <undefined> 

how can fix this?

univeral_newlines=true enables text mode. subprocess output (bytes) decoded using locale.getpreferredencoding(false) character encoding @cdosborn mentioned.

if doesn't work, provide actual encoding used command. and/or specify error handler such 'ignore','surrogateescape', etc errors parameter:

from subprocess import popen, pipe  def __executecommand(self, command: str, input: str = none,                       encoding=none, errors='strict') -> str:     text_mode = (encoding none)     popen(command, stdout=pipe, stderr=pipe, stdin=pipe,                universal_newlines=text_mode) p:         if input not none , not text_mode:             input = input.encode(encoding, errors) # convert bytes         output, err = p.communicate(input)     if err or p.returncode != 0:          raise environmenterror("could not generate key. "                                "error: {}, return value: {}".format(                                    ascii(err), p.returncode))     return output if text_mode else output.decode(encoding, errors)