awk学习笔记之一BEGIN和END

 BEGIN语句使用在任何文本浏览动作之前，之后文本浏览动作依据输入文件开始执行。单是这样看一头雾水，下面做个实验就清楚啦~~

 

[root@demo ~]# cat awk1.t
reed 100 90 100 1
deer 99  91  99 2
hjl  92  100 80 3
gsl  80  80  80 5
zww  85  85  85 4
[root@demo ~]# awk '{print "name\tthe 2nd number\n----------------"}{print $1"\t"$2}' awk1.t
name    the 2nd number
----------------
reed    100
name    the 2nd number
----------------
deer    99
name    the 2nd number
----------------
hjl     92
name    the 2nd number
----------------
gsl     80
name    the 2nd number
----------------
zww     85
[root@demo ~]# awk 'BEGIN{print "name\tthe 2nd number\n----------------"}{print $1"\t"$2}' awk1.t
name    the 2nd number
----------------
reed    100
deer    99
hjl     92
gsl     80
zww     85

 END语句用来在a w k完成文本浏览动作后打印输出文本总数和结尾状态标志。

 

[root@demo ~]# awk 'BEGIN{print "2nd\t3rd\n----------------"}{a+=$2}{b+=$3}{print a"\t"b}' awk1.t
2nd     3rd
----------------
100     90
199     181
291     281
371     361
456     446
[root@demo ~]# awk 'BEGIN{print "2nd\t3rd\n----------------"}{a+=$2}{b+=$3}END{print a"\t"b}' awk1.t
2nd     3rd
----------------
456     446
[root@demo ~]#

有例子看就很明白啦~~