我可以在 Unix 中运行 jshell 吗？

我想使用expect重定向jshell输入，以便我可以在录制的演示中模拟输入。但是，尽管我可以从 Expect 脚本生成一个 jshell 进程，该进程也可以识别 jshell 提示符，但之后就没有任何效果了。期望输出看起来像控制序列，例如^[[24;9R，并且我没有看到 jshell 的任何输出。不同的终端类型会产生不同的字符序列，但它们都不起作用。此行为在 Ubuntu 和 Mac OS 上的 Expect 之间是一致的。欢迎任何有关如何调查此问题的建议。expect -d没有帮助。

这是我想要模拟的 jshell 会话的记录

$ jshell
|  Welcome to JShell -- Version 9.0.1
|  For an introduction type: /help intro

jshell> 3
$1 ==> 3

jshell> 

这是我认为应该执行此操作的脚本：

#!/usr/bin/expect -f
spawn jshell
expect jshell>
send "3\r"
expect jshell>

当我运行该脚本时（在 Mac OS 10.11.6 上，但在 Ubuntu 上得到非常相似的结果），我看到以下输出

spawn jshell
|  Welcome to JShell -- Version 9.0.1
|  For an introduction type: /help intro

jshell> ^[[24;9R

然后expect超时，并且最后一行输出被shell提示符覆盖（因此看起来好像在超时时正在写入更多控制字符）。

Adding -d脚本第 1 行中的 Expect 标志会产生以下输出：

expect version 5.45
argv[0] = /usr/bin/expect  argv[1] = -d  argv[2] = -f  argv[3] = ./expectscript
set argc 0
set argv0 "./expectscript"
set argv ""
executing commands from command file ./expectscript
spawn jshell
parent: waiting for sync byte
parent: telling child to go ahead
parent: now unsynchronized from child
spawn: returns {19712}

expect: does "" (spawn_id exp8) match glob pattern "jshell>"? no
|  Welcome to JShell -- Version 9.0.1
|  For an introduction type: /help intro

expect: does "|  Welcome to JShell -- Version 9.0.1\r\n|  For an introduction type: /help intro\r\n" (spawn_id exp8) match glob pattern "jshell>"? no

jshell>
expect: does "|  Welcome to JShell -- Version 9.0.1\r\n|  For an introduction type: /help intro\r\n\r\njshell> " (spawn_id exp8) match glob pattern "jshell>"? yes 
expect: set expect_out(0,string) "|  Welcome to JShell -- Version 9.0.1\r\n|  For an introduction type: /help intro\r\n\r\njshell> "
expect: set expect_out(spawn_id) "exp8"
expect: set expect_out(buffer) "|  Welcome to JShell -- Version 9.0.1\r\n|  For an introduction type: /help intro\r\n\r\njshell> "
send: sending "3\r" to { exp8 }

expect: does "" (spawn_id exp8) match glob pattern "jshell>"? no

expect: does "\u001b[6n" (spawn_id exp8) match glob pattern "jshell>"? no
^[[32;1Rexpect: timed out

设法让它工作（在 Debian 9.3 上使用 jshell 9.0 和 Expect 5.45 进行测试）：

[STEP 103] # cat jshell.exp
proc expect_prompt {} {
    upvar spawn_id spawn_id

    expect -ex "jshell> "

    # the CPR (cursor position report) code
    expect -ex "\x1b\[6n"

    # read the CPR result and send it the application
    expect_tty -re {\x1b\[[0-9]+;[0-9]+R}
    send $expect_out(0,string)
}

stty raw; # give tty's full control to jshell since it's crazy

spawn jshell
expect_prompt

send "3\r"
expect_prompt

send "/exit\n"
expect eof
[STEP 104] # expect jshell.exp
spawn jshell
|  Welcome to JShell -- Version 9.0.1
|  For an introduction type: /help intro

jshell> 3
$1 ==> 3

jshell> /exit
|  Goodbye
[STEP 105] #

魔法是关于CPR（光标位置报告）（搜索CPR在页面上）。

1. The ^[[6n (^[ == ESC == 0x1b == \u001b) is the CPR request (sent by jshell).
2. 字符串像^[[32;1R（第 32 行，第 1 列）是当前光标位置（由终端驱动程序生成并由jshell).