比較輸出

Question

我有以下代碼是從一個問題的工作分開。我試圖比較來自commands.getoutput（cmd）的兩個輸出，但即時獲取語法錯誤。據我所知，這可能是天生錯的，但也有人指出在做什麼我錯了

def DiffGenerator(): 

    try: sys.argv[1] 
    except: print "No Directory to scan defined\n" 

    try: sys.argv[2] 
    except: print "No delay time defined\n" 

    ScanDirectory = sys.argv[1] 
    if not os.path.exists(ScanDirectory): 
    print "Scan Directory does not exist :" + ScanDirectory 

    cmd = "ls -l " + ScanDirectory 

    try: 
    DiffFileA = commands.getoutput(cmd) 
    print "Printing DiffFileA" + DiffFileA 
    time.sleep(1) 
    DiffFileB = commands.getoutput(cmd) 
    if operator.ne(DiffFileA, DiffFileB) 
     print "New File placed within " + ScanDirectory 
    except: 
    print "BLAH" 

Answer 1

你可能要考慮子

http://docs.python.org/library/subprocess.html

subprocess.Popen(['ls','-a'], stdout = subprocess.PIPE, stdin = subprocess.PIPE) 
results = subprocess.communicate()[0] #where [0] is the stdout and [1] is the stderr 

編輯：

也可以你可以擴大你的嘗試除了循環，並使用特定的例外，例如

壞：

try: sys.argv[1] 
except: print "No Directory to scan defined\n" 

好：

try: 
    sys.argv[1] 
except IndexError: 
    print "No directory to scan defined\n" 

Answer 2

線if operator.ne(DiffFileA, DiffFileB)缺少一個冒號，這可以解釋一個SyntaxError。順便說一句，報告錯誤時，請複製並粘貼正是您看到的錯誤消息。

但如果使用operator.ne（A，B）：是寫一個非常unpythonic方式，如果A = B：和我儘量吧！