管道命令在python结构中不起作用

我试图通过管道传输多个bash命令，从列出图像名称的命令的输出中提取图像名称，但它不起作用-它会吐出一团文本，就像一步一步地做一样

使用管道的代码：

@task
def update():
    image_name = sudo('/os-updater --list | grep X86-64_ | sed "s/XXX/UEK4/" | tail -1')
    print("IMAGE NAME: "+image_name)

输出：

user@system:host-updater$ ./hu -R host-name update
[host-name] Executing task 'update'
[host-name] sudo: /os-updater --list | grep X86-64_ | sed "s/XXX/UEK4/" | tail -1
[host-name] out: 2018-01-11 23:33:28,628 INFO ==> os-updater 1.3.3 started
[host-name] out: 2018-01-11 23:33:28,629 INFO --listsnapshots:True
[host-name] out: 2018-01-11 23:33:28,705 INFO Exit 0
[host-name] out:   X86-64_20171201.01_UEK4
[host-name] out: 

IMAGE NAME: 2018-01-11 23:33:28,628 INFO ==> os-updater 1.3.3 started
2018-01-11 23:33:28,629 INFO --listsnapshots:True
2018-01-11 23:33:28,705 INFO Exit 0
  X86-64_20171201.01_UEK4

Done.

user@system:host-updater$ ./hu -R host-name update
[host-name] Executing task 'update'
[host-name] sudo: /os-updater --list
[host-name] out: 2018-01-11 23:36:11,752 INFO ==> os-updater 1.3.3 started
[host-name] out: 2018-01-11 23:36:11,753 INFO --listsnapshots:True
[host-name] out: 2018-01-11 23:36:11,847 INFO Exit 0
[host-name] out: Snapshots:
[host-name] out:   X86-64_20171101.01_XXX
[host-name] out:   X86-64_20171201.01_XXX
[host-name] out: Kernel trains: (XXX above)
[host-name] out:   UEK4
[host-name] out:   STOCK
[host-name] out: 

IMAGE NAME: X86-64_20171201.01_UEK4

Done.

不带pipleine的代码：

@task
def update():
    image_list = sudo("/os-updater --list")
    out = image_list.stdout
    for line in out.splitlines():
        if 'X86-64_' in line:
            image_name = line.replace("XXX", "UEK4").strip()

    print("IMAGE NAME: " + image_name)

输出：

user@system:host-updater$ ./hu -R host-name update
[host-name] Executing task 'update'
[host-name] sudo: /os-updater --list | grep X86-64_ | sed "s/XXX/UEK4/" | tail -1
[host-name] out: 2018-01-11 23:33:28,628 INFO ==> os-updater 1.3.3 started
[host-name] out: 2018-01-11 23:33:28,629 INFO --listsnapshots:True
[host-name] out: 2018-01-11 23:33:28,705 INFO Exit 0
[host-name] out:   X86-64_20171201.01_UEK4
[host-name] out: 

IMAGE NAME: 2018-01-11 23:33:28,628 INFO ==> os-updater 1.3.3 started
2018-01-11 23:33:28,629 INFO --listsnapshots:True
2018-01-11 23:33:28,705 INFO Exit 0
  X86-64_20171201.01_UEK4

Done.

user@system:host-updater$ ./hu -R host-name update
[host-name] Executing task 'update'
[host-name] sudo: /os-updater --list
[host-name] out: 2018-01-11 23:36:11,752 INFO ==> os-updater 1.3.3 started
[host-name] out: 2018-01-11 23:36:11,753 INFO --listsnapshots:True
[host-name] out: 2018-01-11 23:36:11,847 INFO Exit 0
[host-name] out: Snapshots:
[host-name] out:   X86-64_20171101.01_XXX
[host-name] out:   X86-64_20171201.01_XXX
[host-name] out: Kernel trains: (XXX above)
[host-name] out:   UEK4
[host-name] out:   STOCK
[host-name] out: 

IMAGE NAME: X86-64_20171201.01_UEK4

Done.

我不明白为什么第二种方法（字面上是一步一步地做相同的事情，没有管道）有效，但第一种方法却不能返回大量带有图像名称的文本。 我试过很多东西：

image_name = sudo('/opt/os-updater/bin/os-updater --list | grep X86-64_OL7_ | sed "s/XXX/UEK4/" | tail -1').stdout.strip() 

然后使用fabric隐藏选项运行命令，如

#with hide（'output'，'running'，'warnings'）：

。这些都不管用。

---

管道不起作用真是太奇怪了。非常感谢您的帮助。

管道是一个shell语法元素。您需要在shell中运行它：

sudo("/os-updater --list | sed -n '/X86-64_/s/XXX/UEK4/p' | tail -1", shell=True)

---

PS：我自由地将

grep

和

sed

命令组合成一个命令。

谢谢。但这也不行。它仍然返回那一团文本。尝试了以下方法：image_name=sudo（“/os updater--list | sed-n'/X86-64_/s/XXX/UEK4/p'| tail-1”，shell=True）打印（“image_name:+image_name”）获得相同的：IMAGE\u NAME:2018-01-12 18:58:52964 INFO==>os updater 1.3.3已启动2018-01-12 18:58:52965 INFO--listsnapshots:True 2018-01-12 18:58:53052 INFO退出0 X86-64\u 20171201.01\u UEK4