ssh - 如何在 TCL Expect 中的多个程序之间共享一个衍生的 SSH 进程？

Question

编辑:我通过引用 Exploring Expect 书找到了答案。不过，请不要犹豫，添加到我的答案或提出其他建议!当我被允许(从现在起 2 天)时，我会将其标记为已回答。

我环顾四周，不幸的是，我无法在此站点上找到太多关于使用 SSH 和 expect 的信息。我对 Expect 比较陌生，但我一直在用 Exploring Expect 书自学。

我的问题是:如何将一个衍生的 SSH 进程用于多个 tcl 程序？我现在的解决方法是在程序 1 结束时关闭 SSH 连接，并在程序 2 中重新生成一个新的 SSH 连接。

示例:(示例被简化了很多，仅包含演示我的问题的必要组件......我的整个程序现在已经超过 200 行)

;# Proc definition for procedure1
    proc procedure1 {user host pw} {
     spawn /usr/bin/ssh $user@$host
     expect "Password:"
     send "$pw\r"
     expect "#" ;# This is my device's prompt
     ;# From here it does a bunch of stuff... sends commands to the SSH
     ;# session, captures output, builds arrays and lists, etc
     send "exit" ;# Disconnects the SSH session
     return $mylist ;# returns a list of numbers to be used in procedure 2
     }

;# Proc definition for procedure2
    proc procedure2 {resultofproc1 user host pw} {    
     spawn /usr/bin/ssh $user@$host
     expect "Password:"
     send "$pw\r"
     expect "#" ;# This is my device's prompt
     ;# Proc 2 now continues on in the same device using the results (a 
     ;# list) from proc1. 
     return
    }



    ;# Procedure call for first procedure:
    set resultofproc1 "[procedure1 $user $host $pw]"

    ;# Procedure call for second procedure:
    procedure2 $resultofproc1 $user $host $pw

与在程序 1 结束时关闭 SSH 连接并在程序 2 开始时重新打开 SSH 连接不同，如何将程序 2 中的命令发送到程序 1 中打开的 SSH 连接？显然，我必须删除退出的发送以保持连接打开。假设这是可能的......这甚至是一个好习惯还是我最好分离程序之间的连接？如果是这样，您可以修改我的代码示例以演示如何吗？

根据我收集到的信息，我认为它与 spawn_id 变量有关。但我不知道如何在我的代码中实现它。我目前正在查看 Exploring Expect 一书中的第 10 章“处理多个进程”。如果我能自己解决，我会报告。

感谢你的协助!

我在stackoverflow上查看了这些答案:

Tcl Expect Keep SSH Spawn open

Expect Procedure for SSH Login

Using procedure for spawing SSH doesn't work properly with expect

Answer 1

您可以使用global申报spawn_id作为全局变量。根据期望的手册:

CAVEATS

...
Expect takes a rather liberal view of scoping. In particular, variables read by commands specific to the Expect program will be sought first from the local scope, and if not found, in the global scope. For example, this obviates the need to place global timeout in every procedure you write that uses expect. On the other hand, variables written are always in the local scope (unless a global command has been issued). The most common problem this causes is when spawn is executed in a procedure. Outside the procedure, spawn_id no longer exists, so the spawned process is no longer accessible simply because of scoping. Add a global spawn_id to such a procedure.
...

您还可以利用 Tcl 的 upvar命令。例如:

[STEP 101] $ cat foo.exp
proc expect_prompt {} {
    upvar spawn_id spawn_id
    expect -re {bash-[.0-9]+[#$] $}
}

proc open_conn {} {
    upvar spawn_id spawn_id
    spawn bash --noprofile --norc
    expect_prompt
}

proc close_conn {} {
    upvar spawn_id spawn_id
    send "exit\r"
    expect eof
}

proc send_cmd { cmd } {
    upvar spawn_id spawn_id
    send "$cmd\r"
    expect_prompt
}

proc main {} {
    open_conn

    send_cmd "echo spawn_id=$spawn_id"
    send_cmd "ps Tu"

    close_conn
}

main
[STEP 102] $ 

输出:

[STEP 103] $ expect foo.exp
spawn bash --noprofile --norc
bash-4.4$ echo spawn_id=exp6
spawn_id=exp6
bash-4.4$ ps Tu
USER     PID  %CPU %MEM      VSZ    RSS   TT  STAT STARTED      TIME COMMAND
root   71513   0.0  0.0  2433012    788 s013  R+   12:58PM   0:00.00 ps Tu
pynexj 71510   0.0  0.0  2445360   1572 s013  Ss   12:58PM   0:00.01 bash --noprofile --norc
bash-4.4$ exit
exit
[STEP 104] $