Question

可能重复：
converting string to lower case in bash shell scripting

例如：

 echo *****Language translator*****
 echo please choose the language
 for Chinese enter c
 for French enter f

以简单的方式，我希望能够识别中文的C和c; 和F和F一样，被认为是法国人。

有没有办法将所有内容转换为小写？

这部分代码：

如果[$ language == c];
      然后
        echo“输入要翻译的单词：”
        阅读word_to_translate

Answer 1

您可以使用tr将字符切换为小写/大写：

echo $language | tr '[A-Z]' '[a-z]'

Answer 2

您可以使用以下案例修饰符（来自man bash）：

${parameter^}      # Convert the first character in ${parameter} to uppercase
${parameter^^}     # Convert all characters in ${parameter} to uppercase
${parameter,}      # Convert the first character in ${parameter} to lowercase
${parameter,,}     # Convert all characters in ${parameter} to lowercase

所以你的代码看起来像这样：

# Read one character into $lang, with a nice prompt.
read -n 1 -p "Please enter c for Chinese, or f for French: " lang
if [ "${lang,,}" == "c" ]; then
  echo "Chinese"
elif [ "${lang,,}" == "f" ]; then
  echo "French"
else
  echo "I don't speak that language."
fi

Answer 3

现代版本的tr支持POSIX字符类[：upper：]和[：lower：]

tr -s '[:upper:]'  '[:lower:]' < inputfile > outputfile

所有角色类都在这里：

http://ss64.com/bash/tr.html

Answer 4

我可能会使用案例陈述，但还有其他方法可以做到：

read language
case "$language" in
([cC]) echo 'Chinese';;
([fF]) echo 'French';;
(*)    echo 'Unrecognized language abbreviation';;
esac

如果您需要交换机外的值，您可以在case中进行规范分配：

read language
case "$language" in
([cC]) lingua='zh_tw'; echo 'Chinese';;
([fF]) lingua='fr_fr'; echo 'French';;
(*)    echo 'Unrecognized language abbreviation';;
esac

如何在Bash中将大写转换为小写或反过来？

4 个答案: