针对其他人：

您不需要在BASH4中指定大小写，只需使用'，，'使var小写即可。此外，我强烈不喜欢将代码放在读取块内，获取结果并在读取块IMO外处理它。还包括一个“q”表示退出IMO。最后，为什么键入“yes”只需使用-n1并按y。

示例：用户可以按y/n和q退出。

ans=''
while true; do
    read -p "So is MikeQ the greatest or what (y/n/q) ?" -n1 ans
    case ${ans,,} in
        y|n|q) break;;
        *) echo "Answer y for yes / n for no  or q for quit.";;
    esac
done

echo -e "\nAnswer = $ans"

if [[ "${ans,,}" == "q" ]] ; then
        echo "OK Quitting, we will assume that he is"
        exit 0
fi

if [[ "${ans,,}" == "y" ]] ; then
        echo "MikeQ is the greatest!!"
else
        echo "No? MikeQ is not the greatest?"
fi

在这种情况下，我已经多次使用case语句，使用case语句是一种很好的方法。可以实现while循环，该循环模拟case块，利用布尔条件，以便更好地控制程序，并满足许多其他要求。在满足所有条件后，可以使用中断，将控制权传递回程序的主要部分。此外，为了满足其他条件，当然可以在控制结构中添加条件语句：case语句和可能的while循环。

使用案例陈述来满足您的请求的示例

#! /bin/sh 

# For potential users of BSD, or other systems who do not
# have a bash binary located in /bin the script will be directed to
# a bourne-shell, e.g. /bin/sh

# NOTE: It would seem best for handling user entry errors or
# exceptions, to put the decision required by the input 
# of the prompt in a case statement (case control structure), 

echo Would you like us to perform the option: "(Y|N)"

read inPut

case $inPut in
    # echoing a command encapsulated by 
    # backticks (``) executes the command
    "Y") echo `Do something crazy`
    ;;
    # depending on the scenario, execute the other option
    # or leave as default
    "N") echo `execute another option`
    ;;
esac

exit

echo "Please enter some input: "
read input_variable
echo "You entered: $input_variable"

是/否/取消

作用

#!/usr/bin/env bash
@confirm() {
  local message="$*"
  local result=''

  echo -n "> $message (Yes/No/Cancel) " >&2

  while [ -z "$result" ] ; do
    read -s -n 1 choice
    case "$choice" in
      y|Y ) result='Y' ;;
      n|N ) result='N' ;;
      c|C ) result='C' ;;
    esac
  done

  echo $result
}

用法

case $(@confirm 'Confirm?') in
  Y ) echo "Yes" ;;
  N ) echo "No" ;;
  C ) echo "Cancel" ;;
esac

使用干净的用户输入进行确认

作用

#!/usr/bin/env bash
@confirm() {
  local message="$*"
  local result=3

  echo -n "> $message (y/n) " >&2

  while [[ $result -gt 1 ]] ; do
    read -s -n 1 choice
    case "$choice" in
      y|Y ) result=0 ;;
      n|N ) result=1 ;;
    esac
  done

  return $result
}

用法

if @confirm 'Confirm?' ; then
  echo "Yes"
else
  echo "No"
fi

作为单行命令的朋友，我使用了以下命令：

while [ -z $prompt ]; do read -p "Continue (y/n)?" choice;case "$choice" in y|Y ) prompt=true; break;; n|N ) exit 0;; esac; done; prompt=;

以长格式编写，其工作原理如下：

while [ -z $prompt ];
  do read -p "Continue (y/n)?" choice;
  case "$choice" in
    y|Y ) prompt=true; break;;
    n|N ) exit 0;;
  esac;
done;
prompt=;

可以在POSIX shell中处理区域设置感知的“是/否选项”；通过使用LC_MESSAGES语言环境类别的条目，witch提供了与输入匹配的现成RegEx模式，以及本地化Yes No的字符串。

#!/usr/bin/env sh

# Getting LC_MESSAGES values into variables
# shellcheck disable=SC2046 # Intended IFS splitting
IFS='
' set -- $(locale LC_MESSAGES)

yesexpr="$1"
noexpr="$2"
yesstr="$3"
nostr="$4"
messages_codeset="$5" # unused here, but kept as documentation

# Display Yes / No ? prompt into locale
echo "$yesstr / $nostr ?"

# Read answer
read -r yn

# Test answer
case "$yn" in
# match only work with the character class from the expression
  ${yesexpr##^}) echo "answer $yesstr" ;;
  ${noexpr##^}) echo "answer $nostr" ;;
esac

编辑：正如@Urhixidur在评论中提到的：

不幸的是，POSIX只指定了前两个（yeexpr和noexpr）。在Ubuntu 16上，yestr和nostr为空。

参见：https://www.ee.ryerson.ca/~courses/ele709/susv4/xrat/V_4_xbd_chap07.html#tag_21_07_03_06

LC_消息yestr和nostr语言环境关键字以及yesstr和nostr语言信息项以前用于匹配用户的肯定和否定响应。在POSIX.1-2008中，yeexpr、noexpr、yesexpr和noexpr扩展正则表达式已取代它们。应用程序应该使用通用的基于语言环境的消息传递工具来发出包含所需响应示例的提示消息。

或者使用Bash方式的区域设置：

#!/usr/bin/env bash

IFS=$'\n' read -r -d '' yesexpr noexpr _ < <(locale LC_MESSAGES)

printf -v yes_or_no_regex "(%s)|(%s)" "$yesexpr" "$noexpr"

printf -v prompt $"Please answer Yes (%s) or No (%s): " "$yesexpr" "$noexpr"

declare -- answer=;

until [[ "$answer" =~ $yes_or_no_regex ]]; do
  read -rp "$prompt" answer
done

if [[ -n "${BASH_REMATCH[1]}" ]]; then
  echo $"You answered: Yes"
else
  echo $"No, was your answer."
fi

使用语言环境提供的regexp来匹配答案。

要翻译剩余的消息，请使用bash--dump po string scriptname输出po字符串以进行本地化：

#: scriptname:8
msgid "Please answer Yes (%s) or No (%s): "
msgstr ""
#: scriptname:17
msgid "You answered: Yes"
msgstr ""
#: scriptname:19
msgid "No, was your answer."
msgstr ""