linux shell實現位運算

linux shell貌似不支持位運算，所以自己寫了一個位與的實現，以后誰要用可以拿去，實現如下：

 

function yu()
{
bit1=`echo "obase=2;$1" | bc`
    bit2=`echo "obase=2;$2" | bc`
    len1=${#bit1}
    len2=${#bit2}
    if [ "$len1" -gt "$len2" ]
    then
        len=$len1
        bit2=`printf "%0${len}d" $bit2`
        #echo $bit2
    elif [ "$len1" -lt "$len2" ]
    then
        len=$len2
        bit1=`printf "%0${len}d" $bit1`
        #echo $bit1
    else
        len=$len1
    fi 

    for ((i=1;i<=len;i++))
    do 
        b1=${bit1:0-$i:1}
        b2=${bit2:0-$i:1}
        if [ $b1 -eq 1 ] && [ $b2 -eq 1 ] 
        then
            b=1
        else
            b=0
        fi
        result=`echo "$b""$result"`
    done
    result=`echo "obase=10;ibase=2;$result" | bc`
    echo $result
}


a=5
b=2
echo end=`yu $a $b`