Output from Python and Android Fastboot -

i'm creating python script work fastboot commands, , trying

fastboot getvar product 

in order see product have selected. problem when run code:

p = subprocess.popen(['fastboot', "getvar", "all"]) out, err = p.communicate() print "we got: " + out 

out empty. works fine if pass in devices instead of getvar all.

i think has stack overflow question i'm having hard time translating python:

fastboot getvar batch file

how can output getvar in string, instead of outputted terminal?

edit:

i found github account of made similiar function adb, , modified achieve want:

def callfastboot(self, command):     command_result = ''     command_text = 'fastboot %s' % command     results = os.popen(command_text, "r")     while 1:         line = results.readline()         if not line: break         command_result += line     return command_result  out = test.callfastboot("getvar product 2>&1") print "we got: " + out 

the problem uses old os.popen method. new question same, how do subprocess?

for fastboot getvar all need capture stderr instead of stdout:

print subprocess.check_output(['fastboot', 'getvar', 'all'], stderr=subprocess.stdout)