使用Python从多个管道执行Shell脚本

Question

我希望能在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。

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)])

- Vince

---

整个流程可以用单个命令 awk -F= '/limited/ {print gsub("\"", "", $2)}' /etc/xen/$myserver.cfg（应用必要的 $myserver 替换）来替代。 - chepner

Answer 1

您可以将多个子进程粘合在一起：

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，我们已将p2的标准输入设置为p1的标准输出。

编辑：简化了示例。

- Aidan Kane

---

谢谢你的回答！ 我已经编辑了我的帖子。 这样行吗？ - Vince

Answer 2

做到了！ :D 谢谢

dom = myserver    
c1 = ['/bin/cat', '/etc/xen/%s.cfg' % (str(dom))]
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()
subprocess.call(['/root/bin/xen-limit', str(dom), str(result)])

- Vince