bash的if和简单函数

#!/bin/bash
#test for variable
str="hello, andylin"
var="`echo $str`"
echo $var


a=1
b=2
echo $a, $b

if [ "aa" = "aa" ]
then
        echo "aa == aa"
fi

if [ $a -eq $b ]
then
        echo "$a == $b"
elif [ $a -gt $b ]
then
        echo "$a > $b"
else
        echo "$a < $b"
fi

let "a = $a + 1"


function Compare()
{
        echo "compare a & b"
        if [ $a -eq $b ]
        then
                echo "$a == $b"
        elif [ $a -gt $b ]
        then
                echo "$a > $b"
        else
                echo "$a < $b"
        fi
}

Compare