在“期望"中使用条件语句 [英] Using conditional statements inside 'expect'

问题描述

我需要使用 expect 自动登录 TELNET 会话，但我需要处理同一个用户名的多个密码.

I need to automate logging into a TELNET session using expect, but I need to take care of multiple passwords for the same username.

这是我需要创建的流程:

Here's the flow I need to create:

1. 打开与 IP 的 TELNET 会话
2. 发送用户名
3. 发送密码
4. 密码错误?再次发送相同的用户名，然后发送不同的密码
5. 此时应该已成功登录...

就其价值而言，这是我目前所获得的:

For what it's worth, here's what I've got so far:

#!/usr/bin/expect
spawn telnet 192.168.40.100
expect "login:"
send "spongebob
"
expect "password:"
send "squarepants
"
expect "login incorrect" {
  expect "login:"
  send "spongebob
"
  expect "password:"
  send "rhombuspants
"
}
expect "prompt>" {
  send_user "success!
"
}
send "blah...blah...blah
"

不用说这行不通，而且看起来也不是很漂亮.从我在 Google 的冒险经历来看，expect 似乎是一种黑暗艺术.在此先感谢任何人的帮助！

Needless to say this doesn't work, and nor does it look very pretty. From my adventures with Google expect seems to be something of a dark-art. Thanks in advance to anyone for assistance in the matter!

推荐答案

不得不推荐Exploring Expect适合所有期望程序员的书 - 无价之宝.

Have to recomment the Exploring Expect book for all expect programmers -- invaluable.

我已经重写了你的代码:(未经测试)

I've rewritten your code: (untested)

proc login {user pass} {
    expect "login:"
    send "$user
"
    expect "password:"
    send "$pass
"
}

set username spongebob 
set passwords {squarepants rhombuspants}
set index 0

spawn telnet 192.168.40.100
login $username [lindex $passwords $index]
expect {
    "login incorrect" {
        send_user "failed with $username:[lindex $passwords $index]
"
        incr index
        if {$index == [llength $passwords]} {
            error "ran out of possible passwords"
        }
        login $username [lindex $passwords $index]
        exp_continue
    }
    "prompt>" 
}
send_user "success!
"
# ...

exp_continue 循环回到期望块的开头——就像一个重做"语句.

exp_continue loops back to the beginning of the expect block -- it's like a "redo" statement.

注意 send_user 以 结尾，而不是

Note that send_user ends with not

您不必在提示中转义 > 字符:它不是 Tcl 的特殊字符.

You don't have to escape the > character in your prompt: it's not special for Tcl.

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