Run the command progargs with optional input to be fed in to stdin.

def _runcmd(progargs, stdinput=None):
    '''
    Run the command progargs with optional input to be fed in to stdin.
    '''
    stdin = None
    if stdinput is not None:
        assert(isinstance(stdinput, list))
        stdin=PIPE

    err = 0
    output = b''
    log_debug("Calling {} with input {}".format(' '.join(progargs), stdinput))
    try:
        p = Popen(progargs, shell=True, stdin=stdin, 
            stderr=STDOUT, stdout=PIPE, universal_newlines=True)
        if stdinput is not None:
            for cmd in stdinput:
                print(cmd, file=p.stdin)
            p.stdin.close()
        output = p.stdout.read()
        p.stdout.close()
        err = p.wait(timeout=1.0)
    except OSError as e:
        err = e.errno
        log_warn("Error calling {}: {}".format(progargs, e.stderror))
    except Exception as e:
        errstr = str(e)
        log_warn("Error calling {}: {}".format(progargs, errstr))
        err = -1
    log_debug("Result of command (errcode {}): {}".format(err, output))
    return err,output