pexpect 在相同的输入上表现不同

Question

我使用 pexpect 登录瞻博网络防火墙并发送相同的命令两次，我希望输出（我的意思是 s.before）应该是相同的，但它们不是。为什么 pexpect 在同一命令上表现不同？

下面是python测试文件。

import pxssh
import getpass
try:
    s = pxssh.pxssh()
    hostname = '192.168.215.254'
    username = 'root'
    password = 'engine@1'
    s.login (hostname, username, password, original_prompt='root@developfirewall%', auto_prompt_reset=False)
    s.sendline ('cli')  # run a command
    s.PROMPT = 'root@developfirewall>'
    s.prompt()           # match the prompt
    print s.before       # print everything before the prompt.
    s.sendline ('configure')
    s.PROMPT = 'root@developfirewall#'
    s.prompt()
    print s.before
    print 'start---------------------------------------------'
    s.sendline ('delete interfaces ge-0/0/5 unit 0 family inet address 10.123.0.13/32')
    s.prompt()
    print s.before
    print 'end---------------------------------------------'
    print 'start---------------------------------------------'
    s.sendline ('delete interfaces ge-0/0/5 unit 0 family inet address 10.123.0.13/32')
    s.prompt()
    print s.before
    print 'end---------------------------------------------'
    s.logout()
except pxssh.ExceptionPxssh, e:
    print "pxssh failed on login."
    print str(e)

下面是标准输出，我可以看到相同的删除命令返回不同的响应。

 cli


 configure 
Entering configuration mode
Users currently editing the configuration:
  root terminal p1 (pid 64918) on since 2017-11-02 15:18:07 UTC, idle 01:34:05
      [edit]
  root terminal p0 (pid 64649) on since 2017-11-02 14:38:45 UTC, idle 02:07:38
      [edit]
  root terminal p4 (pid 64737) on since 2017-11-02 14:56:05 UTC, idle 01:55:21
      [edit]
The configuration has been changed but not committed

[edit]

start---------------------------------------------
 delete interfaces ge-0/0/5 unit 0 family inet addres
end---------------------------------------------
start---------------------------------------------
 ...0/5 unit 0 family inet address                       10.123.0.13/32 
delete interfaces ge-0/0/5 unit 0 family inet address 10.123.0.13/32warning: statement not found

[edit]

end---------------------------------------------

下面是对juniper防火墙的手动操作，对两个delete命令的响应是一样的。

[clouder@sky27 ~]$ ssh root@juniperfw
--- JUNOS 12.1X44-D35.5 built 2014-05-19 21:36:43 UTC

root@developfirewall% cli
root@developfirewall> configure 
Entering configuration mode
Users currently editing the configuration:
  root terminal p1 (pid 64918) on since 2017-11-02 15:18:07 UTC, idle 01:37:27
      [edit]
  root terminal p4 (pid 64737) on since 2017-11-02 14:56:05 UTC, idle 01:58:43
      [edit]
The configuration has been changed but not committed

[edit]
root@developfirewall# delete interfaces ge-0/0/5 unit 0 family inet address 10.123.0.13/32 
warning: statement not found

[edit]
root@developfirewall# delete interfaces ge-0/0/5 unit 0 family inet address 10.123.0.13/32    
warning: statement not found

[edit]
root@developfirewall# 

Answer 1

可能发生的情况是匹配提示时出现超时，这会导致命令发送过早。 s.prompt() 的默认超时时间是在您使用pxssh.pxssh(timeout=...) 创建对象时设置的，为 30 秒。如果提示调用超时，它将返回 False。

除此之外，您还可以使用print s.before 进行调试，您可以设置一个文件来登录或登录到stderr：pxssh.pxssh(logfile=sys.stderr)。