使用多个管道从Python执行Shell脚本 [英] Execute Shell Script from Python with multiple pipes

问题描述

我想在python脚本中执行以下Shell命令:

I want to execute the following Shell Command in a python script:

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，但是我不知道为什么.

It does not work, but I don't know why..

更新:

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)])

推荐答案

您可以将几个子流程粘合在一起:

You can glue several subprocesses together:

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.

Notice how we've set the stdin of p2 to be the stdout of p1.

简化示例

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