shell比较小数大小

gt,lt 和eq只能对整数操作，那么如果我们想比较小数的大小该怎么办呢？请看下面方法:

 

1. awk -v a=0.7 -v b=0.5 'BEGIN{print(a>b)?"a is big":"b is big"}'

2.

#!/bin/bash
#没对输入位置参数检测
#
c=$(($((${#1}>${#2}?${#1}:${#2}))-2))
ac=$(printf "%.${c}f" $1) ac=${ac/.}
bc=$(printf "%.${c}f" $2) bc=${bc/.}
([[ $ac > $bc ]]&&echo \$1 is big)||\
([[ $ac < $bc ]]&&echo \$2 is big)||\
([[ $ac == $bc ]]&&echo \$1 is equl \$2)

3.

expr $a \> $b
返回1表示$a>$b, 0表示$a<$b

 

4.

适用于bash：

function comp(){
        a=$1
        b=$2

        if [ ${#a} -gt ${#b} ] ; then

                while [ ${#b} -ne ${#a} ]

                do
                        b="0${b}"
                done
        else
                while [ ${#a} -ne ${#b} ]

                do
                        a="0${a}"
                done
        fi

        if [ $a \< $b ] ; then
                echo -1
        elif [ $a \> $b ] ; then
                echo 1
        else
                echo 0
        fi
}

思路：
把数字拆分成整数部分和小数部分，整数部分前面补0对齐，小数部分后面补0对齐。

然后把两个部分作为字符串来比较。

返回结果：
a < b 返回-1
a=b 返回0
a>b 返回1

5.直接作为字符串比较

a=0.7
b=0.5

[ "$a" \> "$b" ] && echo "a>b"

6.bc

 

a=1.6
b=6.1
c=`echo "$a > $b" | bc`