awk 表达式

awk动作表达式中的算数运算符

awk动作表达式中的算数运算符

案例演示

使用awk计算/etc/services中的空白行数

awk 'BEGIN{sum=0}/^$/{++sum}END{print sum}' /etc/services

计算学生课程分数平均值，学生课程文件内容如下

student.txt

Allen    80    90    96    98
Mike    93    98    92    91
Zhang    78    76    87    92
Jerry    86    89    68    92
Han    85    95    75    90
Li    78    88    98    100

　　

awk 'BEGIN{printf "%-20s%-20s%-20s%-20s%-20s%-20s\n","Name","Chinese","English","Math","Physical","Average"}{sum=$2+$3+$4+$5;avg=sum/4}{printf "%-20s%-20d%-20d%-20d%-20d%-0.2f\n",$1,$2,$3,$4,$5,avg}' student.txt

awk 'BEGIN{num1=20;num2+=num1;print num1,num2}'

awk 'BEGIN{num1=20;num2=30;print num1+num2}'

awk 'BEGIN{num1=20;num2=30;print num1-num2}'

awk 'BEGIN{num1=20;num2=30;print num1*num2}'

awk 'BEGIN{num1=20;num2=30;print num1/num2}'

保留小数后两位

awk 'BEGIN{num1=20;num2=30;printf "%0.2f\n",num1/num2}'

awk 'BEGIN{num1=20;num2=3;printf "%0.2f\n",num1**num2}'

awk 'BEGIN{x=20;y=x++;print x,y}'

awk 'BEGIN{x=20;y=++x;print x,y}'

awk 'BEGIN{x=20;y=--x;print x,y}'

输出平均值

awk '{total=$2+$3+$4+$5;AVG=total/4}{printf "%-8s%-5d%-5d%-5d%-8d%0.2f\n",$1,$2,$3,$4,$5,AVG}' student.txt

加上标题并格式化输出

awk 'BEGIN{printf "%-10s%-10s%-10s%-10s%-10s%-10s\n","name","Yuwen","math","English","Pysical","Average"}{total=$2+$3+$4+$5;AVG=total/4}{printf "%-10s%-10d%-10d%-10d%-10d%-10.2f\n",$1,$2,$3,$4,$5,AVG}' student.txt