37、shell编程—awk之条件循环语句

1.条件语句

第一步:创建passwd.awk 文件

BEGIN{
    FS=":"
}
{
    if ($3<50)
    {
        printf "%-20s%-20s%-10d\n","UID<50",$1,$3
    }else if($3>50 || $3<100)
    {
         printf "%-20s%-20s%-10d\n","50100",$1,$3
    }
}

第二步：执行如下命令

awk -f passwd.awk /etc/passwd

2.循环语句

第一步：创建for.awk,while.awk,dowhile.awd文件

BEGIN{
    for(i=0;i<=100;i++)
    {
        sum=sum+i
    }
    print sum
}

BEGIN{

    while(i<=100)
    {
        sum+=i
        i++
    }
    print sum
}

BEGIN{
        do
        {
            sum+=i
            i++
        }while(i<=100)
        print sum
}

第二步：执行如下命令

awk -f for.awk
awk -f while.awk
awk -f dowhile.awk

3.综合

第一步：创建a.txt 文件

name             chinese           english     math   physocal
allen               90                 78       65        69
zhang               70                 75      78        90
xixi                90                 95      87        92
jerry               89                  60      89        76

第二步:创建sore.awk 文件

BEGIN{
        printf "%-10s%-10s%-10s%-10s%-10s%-10s\n","name","chinese","english","math","physocal","avg"
}

{
        total=$2+$3+$4+$5
        avg=total/4
        if (avg>90){
            printf "%-10s%-10d%-10d%-10d%-10d%-0.2f\n",$1,$2,$3,$4,$5,avg
        }
}

第三步：执行如下命令

awk -f sore.awk a.txt

效果如下

name      chinese   english   math      physocal  avg       
xixi      90        95        87        92        91.00