可能逻辑错误

Question

我正在自学 bash

我怎样才能做到这一点？

有三个检查点...没有空行，没有特殊字符和 没有小于 1 和大于最大数的数

然而，在第三个检查点，如果你尝试输入一个特殊字符，整个事情就会像纸牌屋一样翻滚。

如何确保用户没有输入空行、没有特殊字符以及没有小于 1 和大于预定最大数字的数字？

read -p "请输入行号：" line_number

# First checkpoint
# No blank lines accepted as input
while [[ -z "$line_number" ]] ;
do
echo
echo "Line number can not be blank."
echo
read -p "Please enter a valid line number? " line_number
echo
done

# Second checkpoint
# No special characters allowed as input
# Escaping the backtick or accent grave requires three back slashes before the backtick
while [[ $line_number == *['!'@#\$%^\&*()_+?~-\"\\\`]* ]] ; 
do
echo
echo "No special characters allowed"
echo
read -p "Please enter a valid line number? " line_number
echo
done

# Third checkpoint
# No number less than 1 and greater than the $total_line_number
while [[ $line_number -lt 1 || $line_number -gt $total_line_number ]] ; 
do
echo
echo -e "Line number can not be lesser than 1$ and bigger than              $total_line_number."
echo 
read -p "Please enter a number between the 1 and  $total_line_number scope? " line_number
echo
done

Answer 1

如果它应该是行号，则无需区分“常规”字符（如 a）和“特殊”字符（如标点符号）。您唯一要接受的是数字：

line_number=
until [[ $line_number = +([[:digit:]]) &&
         $line_number -ge 1 &&
         $line_number -le $total_line_number  ]]; do
    read -p "Please enter a valid number between 1 and $total_line_number: " line_number
done