linux - 如何检查输入是否为空格和空值？

Question

这是一个示例 bash，您可以通过两种方式看到它:

1)首先

#!/bin/bash

number=0
echo "Your number is: $number"
IFS=' ' read -t 2 -p "Press space to add one to your number: " input

if [ "$input" -eq $IFS ]; then  #OR ==> if [ "$input" -eq ' ' ]; then
    let number=number+1
    echo $number
else
    echo wrong
fi

2)其次:

#!/bin/bash

number=0
echo "Your number is: $number"
read -t 2 -p "Press space to add one to your number: " input

case "$input" in  
    *\ * )
        let number=$((number+1))
        echo $number
        ;;
    *)
        echo "no match"
        ;;
esac

现在问题:

这两种方式，如何判断输入参数是white space还是null？

我想在 bash 中同时检查 white space 或 null。

谢谢

Answer 1

你可以尝试这样的事情:

#!/bin/bash

number=0
echo "Your number is: $number"
IFS= read -t 2 -p "Press space to add one to your number: " input
# Check for Space
if [[ $input =~ \ + ]]; then
    echo "space found"
    let number=number+1
    echo "$number"
# Check if input is NULL
elif [[ -z "$input" ]]; then
    echo "input is NULL"
fi