在使用嵌套产卵方法期望脚本

Question

我写了下面的expect脚本：

/usr/bin/expect<<EOF 
set SERVER_HOSTNAME "$env(SERVER_HOSTNAME)" 

set USERNAME "$env(USERNAME)" 
set PASSWORD "$env(PASSWORD)" 

set timeout -1 

spawn ssh "$USERNAME@$SERVER_HOSTNAME" 
expect { 
     "Host key verification failed." { spawn ssh-keygen -R "$SERVER_HOSTNAME"; expect "known_hosts.old"; send_user "Updated host key details."; exp_continue} 
     "continue connecting (yes/no)" { send "yes\r"; expect "Permanently added"; exp_continue} 
     "assword:" { send_user "Keygen details are correctly mapped for this server\n"} 
     } 
EOF 

在这里，我想，如果同时spawing“SSH”的过程，那么嵌套的服务器的主机密钥无法验证产卵过程“ssh-keygen -R”应该删除旧密钥。然后，“ssh”进程应该尝试再次连接，以便可以添加与该服务器相对应的新密钥。

但在这里，执行后：

send_user "Updated host key details." 

方法，希望过程是从这个脚本退出了。

我知道替代可以分化这个期待调入两个步骤，如下所示：

/usr/bin/expect<<EOF 
set SERVER_HOSTNAME "$env(SERVER_HOSTNAME)" 

set USERNAME "$env(USERNAME)" 
set PASSWORD "$env(PASSWORD)" 

set timeout -1 

spawn ssh "$USERNAME@$SERVER_HOSTNAME" 
expect { 
     "Host key verification failed." { spawn ssh-keygen -R "$SERVER_HOSTNAME"; expect "known_hosts.old"; send_user "Updated host key details."; exp_continue}    
     "continue connecting (yes/no)" { send "yes\r"; expect "Permanently added"; exp_continue} 
     "assword:" { send_user "Keygen details are correctly mapped for this server\n"} 
     } 


spawn ssh "$USERNAME@$SERVER_HOSTNAME" 
expect {   
     "continue connecting (yes/no)" { send "yes\r"; expect "Permanently added"; exp_continue} 
     "assword:" { send_user "Keygen details are correctly mapped for this server\n"} 
     } 

EOF  

但是，我们有办法在一个去执行该期望的呼叫。简而言之，我想知道，我们可以做产卵过程的嵌套吗？

Answer 1

空白对可维护的代码有很大的帮助：你不需要在每行压缩这么多的命令。

spawn ssh "$USERNAME@$SERVER_HOSTNAME" 
expect { 
    "Host key verification failed." { 
     spawn ssh-keygen -R "$SERVER_HOSTNAME" 
     expect "known_hosts.old" 
     send_user "Updated host key details." 
     exp_continue 
    } 
    "continue connecting (yes/no)" { 
     send "yes\r" 
     expect "Permanently added" 
     exp_continue 
    } 
    "assword:" { 
     send_user "Keygen details are correctly mapped for this server\n" 
    } 
} 

我这种情况下，你不需要使用ssh-凯基互动，所以使用exec简单地称之为

"Host key verification failed." { 
     exec ssh-keygen -R "$SERVER_HOSTNAME" 
     puts "Updated host key details." 
     exp_continue 
    } 

如果你需要生成的东西，与它进行交互，你需要要知道有一个隐含变量，由spawn创建并由expect和send使用。在生成任何其他进程之前，您需要保存当前进程的spawn_id。例如：

spawn process1 
set ids(1) $spawn_id 
expect -i $ids(1) "some pattern" 
send -i $ids(1) "some string\r" 

spawn process2 
set ids(2) $spawn_id 
expect -i $ids(2) "some pattern from process2" 
send -i $ids(2) "some string to process2\r"