在bash腳本中比較數字

Question

我編寫此腳本的目的是比較bash中的2個數字，但對於某些數字卻給出了錯誤的答案。 就像我給它2＆2作為輸入一樣，它給我“ X大於Y”

#!/bin/bash 
read num1
read num2
if [ $num1 > $num2 ]
    then 
        echo "X is greater than Y"
elif [ $num1 < $num2 ]
    then 
        echo "X is less than Y"
elif [ $num1 = $num2 ]
    then 
        echo "X is equal to Y"
fi 

Answer 1

您可以嘗試使用bash算術上下文：

#!/bin/bash 
read num1
read num2
if (( num1 > num2 ))
    then 
        echo "X is greater than Y"
elif (( num1 < num2 ))
    then 
        echo "X is less than Y"
elif (( num1 == num2 ))
    then 
        echo "X is equal to Y"
fi 

Answer 2

這對我有用：

cmp() {
    num1="$1"
    num2="$2"

    if [ $num1 -gt $num2 ]
        then 
            echo "X is greater than Y"
    elif [ $num1 -lt $num2 ]
        then 
            echo "X is less than Y"
    elif [ $num1 -eq $num2 ]
        then 
            echo "X is equal to Y"
    fi
}

然后查看結果：

cmp 2 3
X is less than Y

cmp 2 2
X is equal to Y

cmp 2 1
X is greater than Y

由於您使用的是bash ，因此建議您使用[[ ... ]]而不是[ ... ]方括號。

Answer 3

#!/bin/sh

echo hi enter first  number
read num1 

echo hi again enter second number
read num2

if [ "$num1" -gt "$num2" ]
then
  echo $num1 is greater than $num2
elif [ "$num2" -gt "$num1" ]
then
  echo $num2 is greater than $num1
else
  echo $num1 is equal to $num2
fi

（請注意：我們將-gt運算符用於>，-lt表示<，==表示=）

Answer 4

要進行盡可能少的更改，請使用雙括號-進入'double bracket'模式（僅在bash / zsh中有效，在Bourne shell中無效）。

如果要與sh兼容，則可以保持'single bracket'模式，但需要替換所有運算符。

在'single bracket'模式下，像'<','>', '='類'<','>', '='運算符僅用於比較字符串。 要在'single bracket'模式下比較數字，您需要使用'-gt' ， '-lt' ， '-eq'

#!/bin/bash 
read num1
read num2
if [[ $num1 > $num2 ]]
    then 
        echo "X is greater than Y"
elif [[ $num1 < $num2 ]]
    then 
        echo "X is less than Y"
elif [[ $num1 = $num2 ]]
    then 
        echo "X is equal to Y"
fi