shell 编程案例整理

[zheng@localhost ~]$ cat score.txt 
ngsan    80
lisi    81.5
wangwu    93
zhangsan    85
lisi    88
wangwu    97
zhangsan    90
lisi    92
wangwu    88
wangwu    99

[zheng@localhost ~]$ awk 'BEGIN{print "name average total"}{a[$1]+=$2;b[$1]++};END{for(i in a)print i "t"a[i]/b[i]"t"a[i]}' score.txt | column -t
name      average  total
zhangsan  87.5     175
wangwu    94.25    377
ngsan     80       80
lisi      87.1667  261.5

#!/bin/bash

# 求100以内的质数
#declare -i i=1
i=1
while (( i<=100 ))
do
    ret=1
    for ((j=2;j<i;j++))
    do
        # if (( i%j == 0));then
        if [ $(( i%j )) -eq 0 ];then
            ret=0
            break
        fi
    done
    if [ $ret -eq 1 ];then
        echo "$i"
    fi
    # 以下六种运算方式都可以使用
    # (( i=i+1 ))
     i=$[i+1]
    # i=$((i+1))
　　# let i=i+1
　　# let i++
　　# i=`expr $i + 1`
    # 下面这行中的i需要declare为int
    #i=$i+1

done

#!/bin/bash

for ((i=1;i<100;i++))
do
    ret=1
    for ((j=2;j<i;j++))
    do
        if (( i%j == 0 ));then
            ret=0
            break
        fi    
    done
    if ((ret==1));then
        echo $i
    fi
done