如何在期望中转义方括号？

Question

在expect脚本中我无法转义方括号，示例如下，

我有一个 question.sh 脚本如下，

#!/bin/bash
echo "Would you like to specify inputs and execute the script? [Y/n]"
read $REPLY

echo "Deleted Item with ID: 50 and do cleanup? [Y/n]"
read $REPLY

echo "Deleted Item with ID: 51 and do cleanup? [Y/n]"
read $REPLY

echo "Deleted Item with ID: 52 and do cleanup? [Y/n]"
read $REPLY

对于上面的question.sh我有下面的answer.exp，用'expect answer.exp 51'命令执行同样的，

#!/usr/bin/expect -f

set timeout -1

spawn ./question.sh

set item "Deleted Item with ID: "
append item [lindex $argv 0]
append item " and do cleanup? \[Y/n\]"

expect "Would you like to specify inputs and execute the script? \[Y/n\]"
send -- "Y\r"

expect {

      $item {
            send "Y\r"
            exp_continue
      }
      " and do cleanup? \[Y/n\]" {
            send "n\r"
            exp_continue
      }
}

当我使用方括号时，期望不匹配并且不会将答案 (Y/N) 发回。

当我从问题中删除方括号并且答案脚本期望工作正常时，相同，更改后的问题和答案脚本如下。

question.sh：

 #!/bin/bash
echo "Would you like to specify inputs and execute the script? Y/n"
read $REPLY

echo "Deleted Item with ID: 50 and do cleanup? Y/n"
read $REPLY

echo "Deleted Item with ID: 51 and do cleanup? Y/n"
read $REPLY

echo "Deleted Item with ID: 52 and do cleanup? Y/n"
read $REPLY

answer.exp：

#!/usr/bin/expect -f

set timeout -1

spawn ./question.sh

set item "Deleted Item with ID: "
append item [lindex $argv 0]
append item " and do cleanup? Y/n"

expect "Would you like to specify inputs and execute the script? Y/n"
send -- "Y\r"

expect {

      $item {
            send "Y\r"
            exp_continue
      }
      " and do cleanup? Y/n" {
            send "n\r"
            exp_continue
      }
}

Answer 1

expect 命令默认匹配 tcl string match style wildcard patterns，因此[Y/n] 尝试匹配字符 Y、正斜杠或 n 之一。

解决方案：

1. 添加更多反斜杠：

append item " and do cleanup? \\\[Y/n\\\]"

所以它变成了\[Y/N\]。

1. 改用大括号：

append item { and do cleanup? \[Y/n\]}

防止反斜杠的替换。

1. 告诉expect 在每个模式前使用-ex 选项进行精确匹配：

#!/usr/bin/expect -f

set timeout -1

spawn ./question.sh

set item "Deleted Item with ID: "
append item [lindex $argv 0]
append item " and do cleanup? \[Y/n\]"

expect -ex "Would you like to specify inputs and execute the script? \[Y/n\]"
send -- "Y\r"

expect {

      -ex $item {
            send "Y\r"
            exp_continue
      }
      -ex " and do cleanup? \[Y/n\]" {
            send "n\r"
            exp_continue
      }
}