使用多个管道从 Python 执行 Shell 脚本

我想在 python 脚本中执行以下 Shell 命令：

dom=myserver    
cat /etc/xen/$myserver.cfg | grep limited | cut -d= -f2 | tr -d \"

我有这个：

dom = myserver

limit = subprocess.call(["cat /etc/xen/%s.cfg | grep limited | cut -d= -f2", str(dom)])
subprocess.call(['/root/bin/xen-limit', str(dom), str(limit)])

它不起作用，但我不知道为什么..

Update:

c1 = ['cat /etc/xen/%s.cfg']
p1 = subprocess.Popen(c1, stdout=subprocess.PIPE)

c2 = ['grep limited']
p2 = subprocess.Popen(c2, stdin=p1.stdout, stdout=subprocess.PIPE)

c3 = ['cut -d= -f2']
p3 = subprocess.Popen(c3, stdin=p2.stdout, stdout=subprocess.PIPE)

c4 = ['tr -d \"']
p4 = subprocess.Popen(c4, stdin=p3.stdout, stdout=subprocess.PIPE)

result = p4.stdout.read()

limit = subprocess.call([result])
subprocess.call(['/root/bin/xen-limit', str(dom), str(limit)])

您可以将多个子流程粘合在一起：

c1 = ['ls']
p1 = subprocess.Popen(c1, stdout=subprocess.PIPE)

c2 = ['wc']
p2 = subprocess.Popen(c2, stdin=p1.stdout,
                      stdout=subprocess.PIPE)

result = p2.stdout.read()

请注意我们如何将 p2 的标准输入设置为 p1 的标准输出。

编辑：简化示例