Shell 加法
文章目录
1. 两数字相加
#!/usr/bin/env bash echo -n 'Enter the First Number: ' read -r a echo -n 'Enter the Second Number: ' read -r b echo "$a + $b = $((a+b))"
执行：
$ bash addition.sh Enter the First Number: 1 Enter the Second Number: 2 1 + 2 = 3
2. while
#!/bin/bash read -p "请输入一个数字：" num NUM=${num:-100} SUM=0 i=1 while [ $i -le $NUM ] do let SUM+=i let i++ done echo "$SUM"
$ bash sum1.sh 请输入一个数字：10 55
3. for
#!/bin/bash read -p "请输入一个数字：" num NUM=${num:-100} SUM=0 i=1 for i in `seq $NUM` do SUM=$[SUM+i] let i++ done echo "$SUM"
$ bash for1.sh 请输入一个数字：10 55
4. awk（效率更高）
[root@localhost awk]# cat awk1.sh #!/bin/bash sum=0 for((i=0;i<=100000;i++)) do ((sum+=i)) done echo $sum $ bash awk1.sh 5000050000
[root@localhost awk]# cat awk2.sh #!/bin/bash awk 'BEGIN{while(i++<100000)sum+=i;printf("%d\n",sum)}' $ bash awk2.sh 5000050000
