在 Python 中以错误的顺序连接并覆盖部分字符串

Question

我从 Python 脚本中得到一个奇怪的输出

当在循环中运行代码以进行涉及 Paramiko 的实际执行时，它似乎颠倒了要打印的变量的顺序，同时覆盖了输出的开始。

要处理的所有源文本对于两者都是相同的。一个是通过 Paramiko 通过 ssh 从路由器抓取的，另一个是我手动抓取并粘贴为局部变量。

电流输出：

with testis 10.8.11.72 from 10.8.11.72 (10.111.72.1)

具有静态局部变量的所需输出和输出：

Best Path is 10.8.11.73 from 10.8.11.73 (10.111.73.1) with localpref 120

我不知道为什么会这样。请参阅下文了解更多信息和执行。帮助？

代码：

import paramiko

router_channel.send('sh ip bgp 10.23.24.32\n')
buff = ''
best_test =()
while not buff.endswith('#'):
    resp = router_channel.recv(99999)
    buff += resp
#DMVPN variable Declaration.
bgp_show = buff
bgp_list =  bgp_show.split('Local')
bgp_list.pop(0)
for x in bgp_list:
    if 'best' in x:
        best_list = x.split('\n')
        for x in best_list:
            best_list = [x.strip(' ') for x in best_list]
            local_pref = best_list[2]
            local_pref = local_pref.split(',')
            local_pref = local_pref[2]
            best_test = best_list[1]
        print '********'
        print buff
        print '********'
        print "Best Path is " + best_test + " with " + "test"
        print '********'

代码的执行：

dirp@localhost Test Python Scripts]$ python splice.py
    ********
    sh ip bgp 10.23.24.32
    BGP routing table entry for 10.23.24.32/28, version 367886
    Paths: (6 available, best #5, table default)
      Advertised to update-groups:
     1          2          3          4          5          6          7         
     9         
  Refresh Epoch 1
  Local, (Received from a RR-client)
    10.8.111.73 from 10.8.111.73 (10.111.73.2)
      Origin IGP, metric 0, localpref 105, valid, internal
      rx pathid: 0, tx pathid: 0
  Refresh Epoch 2
  Local, (Received from a RR-client)
    10.8.11.72 from 10.8.11.72 (10.111.72.1)
      Origin IGP, metric 0, localpref 120, valid, internal, best
      rx pathid: 0, tx pathid: 0x0
  Refresh Epoch 3
  Local, (Received from a RR-client)
    10.8.11.73 from 10.8.11.73 (10.111.73.1)
      Origin IGP, metric 0, localpref 110, valid, internal
      rx pathid: 0, tx pathid: 0
router#
********
 With testis 10.8.11.72 from 10.8.11.72 (10.111.72.1)
********

静态代码：

bgp_list =  bgp.split('Local')
bgp_list.pop(0)

#pprint.pprint( bgp_list )

#print bgp_list[2]

for x in bgp_list:
    if 'best' in x:
        best_list = x.split('\n')
        for x in best_list:
            best_list = [x.strip(' ') for x in best_list]
            local_pref = best_list[2]
            local_pref = local_pref.split(',')
            local_pref = local_pref[2]
        print '********'
        print bgp
        print '********'
        print "Best Path is " + best_list[1] + ' with' + local_pref
        print '********'    

不将其放入循环而是在本地分配变量时的输出：

derp@localhost Test Python Scripts]$ python splitty1.py 
********
sh ip bgp 10.23.24.32 | exclude local
BGP routing table entry for 10.23.24.32/28, version 122378
  Advertised to update-groups:
     1          2          3          4          5          6          7         
     9         
  Refresh Epoch 1
  Local, (Received from a RR-client)
    10.8.111.72 from 10.8.111.72 (10.111.72.2)
      Origin IGP, metric 0, localpref 105, valid, internal
      rx pathid: 0, tx pathid: 0
  Refresh Epoch 1
  Local, (Received from a RR-client)
    10.8.11.72 from 10.8.11.72 (10.111.72.1)
      Origin IGP, metric 0, localpref 110, valid, internal
      rx pathid: 0, tx pathid: 0
  Refresh Epoch 2
  Local, (Received from a RR-client)
    10.8.11.73 from 10.8.11.73 (10.111.73.1)
      Origin IGP, metric 0, localpref 120, valid, internal, best
      rx pathid: 0, tx pathid: 0x0
  Refresh Epoch 2
  Local
    10.8.11.73 from 10.9.0.1 (10.15.1.41)
      Origin IGP, metric 0, localpref 120, valid, internal
      Originator: 10.111.73.1, Cluster list: 10.15.1.41
      rx pathid: 0, tx pathid: 0
  Refresh Epoch 2
  Local
    10.8.11.73 from 10.8.0.1 (10.15.1.41)
      Origin IGP, metric 0, localpref 120, valid, internal
      Originator: 10.111.73.1, Cluster list: 10.15.1.41
      rx pathid: 0, tx pathid: 0
  Refresh Epoch 2
  Local, (Received from a RR-client)
    10.8.111.73 from 10.8.111.73 (10.111.73.2)
      Origin IGP, metric 0, localpref 115, valid, internal
      rx pathid: 0, tx pathid: 0
********
Best Path is 10.8.11.73 from 10.8.11.73 (10.111.73.1) with localpref 120
********
[derp@localhost Test Python Scripts]$ 

Answer 1

router_channel.recv正在返回 Windows 格式的文本，其中每一行都以'\r\n'. 但是您使用x.split('\n'). 这意味着每一行（可能除了最后一行）都将以'\r'.

在非 Windows 系统上，如果您打印出 ，则会'\r'将光标移回第 1 列而不前进该行。所以，当你这样做时：

print "Best Path is " + best_test + " with " + "test"

您正在打印：

Best Path is blah blah blah\r with test

出来的结果是：

 with testis blah blah blah

最简单的解决方案是使用str.splitlines()方法而不是str.split('\n')。这会自动考虑 Windows 行结尾：

返回字符串中的行列表，在行边界处断开。这种方法使用通用换行方法来分割行......

如果您点击链接，它会解释通用换行符：

一种解释文本流的方式，其中将以下所有内容识别为行结束：Unix 行尾约定'\n'、Windows 约定'\r\n'和旧的 Macintosh 约定'\r'……