bash - 如何检查数字是否在shell中的范围内

Question

我只想在两个值之间插入数字，否则脚本会重复直到数字正确。

这是我的脚本，它不能正常工作:

validation(){
read number
if [ $number -ge 2 && $number -ls 5 ]; then
    echo "valid number"
    break
else
    echo "not valid number, try again"
fi

}

echo "insert number"
validation
echo "your number is" $number

Answer 1

如果您使用的是 Bash，最好使用算术表达式 ((...))为了可读性和灵 active :

if ((number >= 2 && number <= 5)); then
  # your code
fi

循环读取直到输入有效数字:

#!/bin/bash

while :; do
  read -p "Enter a number between 2 and 5: " number
  [[ $number =~ ^[0-9]+$ ]] || { echo "Enter a valid number"; continue; }
  if ((number >= 2 && number <= 5)); then
    echo "valid number"
    break
  else
    echo "number out of range, try again"
  fi
done

((number >= 2 && number <= 5))也可以写成((2 <= number <= 5)) .

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另见:

• Test whether string is a valid integer
• How to use double or single brackets, parentheses, curly braces