Autoexpect Scenario

Autoexpect固然方便，但是很多時候還是必須手動改正Autoexpect所錄製過的script才能順利運行，以下將透過SSH登入本機後執行vmstat的指令來說明：

1. 執行Autoexpect：

# autoexpect

此時系統會產生一個autoexpect的shell環境，並將使用者的動作紀錄起來，離開時請輸入exit指令，之後系統會產生個script.exp的紀錄檔（By default）。

2. 執行script.exp：

lawrence@X60:~/Desktop> ./script.exp

spawn /bin/bash

lawrence@X60:~/Desktop> ssh root@127.0.0.1

Password:

此時會發覺停留在輸入Password:而不再有進一步的動作，這是為何呢？

3. 查看並修正script.exp：

原始script.exp（僅截取錄製的部份）:

set timeout -1

spawn $env(SHELL)

match_max 100000

expect -exact "]2;lawrence@X60:~/Desktop]1;X60lawrence@X60:~/Desktop> "

send -- "ssh root@10"

expect -exact [K"

send -- ""

expect -exact [K"

send -- "127.0.0.1\r"

expect -exact "127.0.0.1\r

The authenticity of host '127.0.0.1 (127.0.0.1)' can't be established.\r

RSA key fingerprint is fa:19:31:7a:ac:04:41:af:4c:38:b7:58:16:a3:14:f8.\r

Are you sure you want to continue connecting (yes/no)? "

send -- "yes\r"

expect -exact "yes\r

Warning: Permanently added '127.0.0.1' (RSA) to the list of known hosts.\r\r

Password: "

send -- "1234\r"

expect -exact "\r

Last login: Fri Mar 12 17:06:12 2010\r\r

Have a lot of fun...\r

[1m[31mX60:~ # [m"

send -- "vmstat -n 1 5\r"

expect -exact "vmstat -n 1 5\r

procs -----------memory---------- ---swap-- -----io---- -system-- -----cpu------\r

r b swpd free buff cache si so bi bo in cs us sy id wa st\r

14 0 25644 20660 26124 464024 0 1 17 23 881 255 7 3 89 1 0\r

0 0 25644 20148 26124 464536 0 0 0 0 1725 2206 6 2 93 0 0\r

0 0 25644 20404 26124 464264 0 0 0 0 1877 2234 3 3 95 0 0\r

0 0 25644 20404 26124 464224 0 0 0 0 1736 2186 4 1 95 0 0\r

0 0 25644 20404 26124 464224 0 0 0 0 1628 2168 3 2 95 0 0\r

[1m[31mX60:~ # [m"

send -- "ex"

expect -exact [K"

send -- ""

expect -exact [K"

send -- "logout\r"

expect -exact "logout\r

Connection to 127.0.0.1 closed.\r\r

]2;lawrence@X60:~/Desktop]1;X60lawrence@X60:~/Desktop> "

send -- "exit\r"

expect eof

問題1:

The authenticity of host '127.0.0.1 (127.0.0.1)' can't be established.\r

RSA key fingerprint is fa:19:31:7a:ac:04:41:af:4c:38:b7:58:16:a3:14:f8.\r

Are you sure you want to continue connecting (yes/no)? "

預設SSH Server/Client連接時，會去紀錄對方的金鑰，也就是因為這個原因，讓expect沒有得到預期的輸出，因為SSH第n次連線後就不需要紀錄彼此的金鑰了。

問題2:

Last login: Fri Mar 12 17:06:12 2010\r\r

Have a lot of fun...\r

^[\[1m^[\[31mX60:~ # ^[(B^[\[m"

每次登入系統的時間一定會是不一樣的，所以把它也註解掉。

問題3:

procs -----------memory---------- ---swap-- -----io---- -system-- -----cpu------\r

r b swpd free buff cache si so bi bo in cs us sy id wa st\r

14 0 25644 20660 26124 464024 0 1 17 23 881 255 7 3 89 1 0\r

0 0 25644 20148 26124 464536 0 0 0 0 1725 2206 6 2 93 0 0\r

0 0 25644 20404 26124 464264 0 0 0 0 1877 2234 3 3 95 0 0\r

0 0 25644 20404 26124 464224 0 0 0 0 1736 2186 4 1 95 0 0\r

0 0 25644 20404 26124 464224 0 0 0 0 1628 2168 3 2 95 0 0\r

^[\[1m^[\[31mX60:~ # ^[(B^[\[m"

當然不需要上一次vmstat的輸出結果，所以也需要註解掉。

修改過後：

set timeout -1

spawn $env(SHELL)

match_max 100000

expect -exact "]2;lawrence@X60:~/Desktop]1;X60lawrence@X60:~/Desktop> "

send -- "ssh root@10"

expect -exact [K"

send -- ""

expect -exact [K"

send -- "127.0.0.1\r"

expect -exact "Password: "

send -- "1234\r"

expect -exact "#"

send -- "vmstat -n 1 5\r"

expect -exact "#"

send -- "ex"

expect -exact [K"

send -- ""

expect -exact [K"

send -- "logout\r"

expect -exact "logout\r

Connection to 127.0.0.1 closed.\r\r

]2;lawrence@X60:~/Desktop]1;X60lawrence@X60:~/Desktop> "

send -- "exit\r"

expect eof

4. 執行：

lawrence@X60:~/Desktop> ./script2.exp

spawn /bin/bash

lawrence@X60:~/Desktop> ssh root@127.0.0.1

Password:

Last login: Mon Mar 22 16:11:29 2010 from localhost

Have a lot of fun...

X60:~ # vmstat -n 1 5

procs -----------memory---------- ---swap-- -----io---- -system-- -----cpu------

r b swpd free buff cache si so bi bo in cs us sy id wa st

0 0 31016 27124 23500 454188 0 1 16 23 880 303 7 3 89 1 0

0 0 31016 29204 23500 451648 0 0 0 20 1815 1834 2 3 95 0 0

0 0 31016 29204 23500 451676 0 0 0 0 1821 1878 2 2 96 0 0

0 0 31016 29700 23500 451232 0 0 0 0 1763 2029 3 2 95 0 0

0 0 31016 29700 23500 451184 0 0 0 0 1807 2241 2 2 95 0 0

X60:~ # logout

Connection to 127.0.0.1 closed.

lawrence@X60:~/Desktop> exit

exit

lawrence@X60:~/Desktop>

Autoexpect雖然有以上的小缺點，但還是能加快script開發的速度。