bash - shell - 将变量放入循环的 ALPHABETICAL 范围内

Question

有什么方法可以将变量放入循环的 ALPHABETICAL 范围内吗？这行不通。

read -p "Where I should start?" start #there will be entered one small letter
for aaa in {$start..z}; do #how put variable $start in range?
...
done

感谢回复。

Answer 1

使用eval扩展变量:

$ s=t
$ eval echo {$s..z}
t u v w x y z

你的例子变成了:

read -p "Where I should start?" start #there will be entered one small letter
for aaa in $(eval echo {$start..z}); do 
echo $aaa
done

由于您有用户输入到 eval，您可能希望首先检查 start 的值是否为单个小写字符:

read -p "Where I should start?" start #there will be entered one small letter
if [[ $start =~ ^[a-y]$ ]]; then 
   for aaa in $(eval echo {$start..z}); do 
   echo $aaa
   done
else 
   echo "Need to use a letter 'a-y'"
fi

您可以阅读更多关于 Bash 大括号扩展的信息 here