Python subprocess.call error message with check_output

Question

So I have:

result = subprocess.check_output(['wine',
                    os.getcwd()+'/static/sigcheck.exe',
                    '-a','-i','-q',
                    self.tmpfile.path()])

But whenever I run this I get this error

CalledProcessError: Command '['wine', '/home/static/sigcheck.exe', '-a', '-i', '-q',     '/tmp/tmpxnsN5j']' returned non-zero exit status 1

But if I change check_output to call it works fine:

Z:\tmp\tmpvOybcm:
    Verified:       Unsigned
    File date:      9:08 AM 10/24/2012
    Publisher:      Hardcore Computer
    Description:    Farthest Emitters Converter
    Product:        Farthest Emitters Converter
    Version:        3.2.0
    File version:   3.2.0
fixme:mscoree:StrongNameSignatureVerificationEx (L"Z:\\tmp\\tmpvOybcm", 1, 0x33ec13): stub
    Strong Name:    Unsigned
    Original Name:  n/a
    Internal Name:  Farthest Emitters Converter
    Copyright:      Hardcore Computer 2006
    Comments:       n/a

Any reason why check_output wouldn't work?

Answer 1

A non-zero return code is (usually) a way of indicating exit with error by a program. So subprocess.check_output will raise an exception if the returncode of the process is non-zero. If you use:

retcode = call(...)

and then print the return code I guess you will see that it is returning 1.

Answer 2

To get output in a string without raising an error on non-zero exit status:

p = Popen(['wine',...], stdout=PIPE)
output = p.communicate()[0]

check_output() executes rc = p.poll() after p.communicate() and raises an error if bool(rc) == True .

Answer 3

Alternative way

proc = subprocess.Popen(['wine',
                    os.getcwd()+'/static/sigcheck.exe',
                    '-a','-i','-q',
                    self.tmpfile.path()], stdin=subprocess.PIPE,  stdout=subprocess.PIPE)
stdout = proc.stdout.read()