Linux Shell 數字計算與比較

直接上指令碼，

使用$(())以及$[]進行數字計算

 數值比較：
n1 -eq n2檢查n1是否等於n2         n1 -le n2檢查n1是否小於等於n2
n1 -ge n2檢查n1是否大於等於n2     n1 -lt n2檢查n1是否小於n2
n1 -gt n2檢查n1是否大於n2         n1 -ne n2檢查n1是否不等於n2

#!/bin/bash
numa=1;
numb=2;
numc1=$(($numa - $numb));
numc2=$[$numa + $numb];
echo "numc1 = $numc1, numc2 = $numc2"

if [ $numc1 -lt 0 ]
then
 echo "numc1 less then 0" 
fi

if [ $numc2 -gt 0 ]
then
 echo "numc2 great then 0"
fi


numd1=$(($numc1 + 9));
numd2=$[$numc2 - 9];

echo "numd1 = $numd1, numd2 = $numd2"

if [ $numd1 -gt $numd2 ]
then
 echo "numd1 great then numd2"
else
 echo "numd1 not great then numd2"
fi

 

 

參考：

http://www.cnblogs.com/linuxer/archive/2012/06/20/2870518.html