awk (一）

awk的高级部分以前没看,就先从awk开始吧,后面再重看sed

随机函数 rand ,srand

[root@x1 ~]# echo a|awk 'BEGIN{srand(PROCINFO["pid"])} {printf "%.0f\n",rand()*11}'

0

[root@x1 ~]# echo a|awk 'BEGIN{srand(PROCINFO["pid"])} {printf "%.0f\n",rand()*11}'

2

[root@x1 ~]# echo a|awk 'BEGIN{srand(PROCINFO["pid"])} {printf "%.0f\n",rand()*11}'

4

[root@x1 ~]# echo a|awk 'BEGIN{srand(PROCINFO["pid"])} {printf "%.0f\n",rand()*11}'

3

awk版随机数生成

#!/bin/sh

awk -v count=$1 -v max=$2 '

BEGIN {

  printf("this programe will genrate %d nums,between 1 to %d\n",count,max)

  for(i=1;i<=count;i++) {

    do {

        srand()

        randnum=1+int(rand()*max)

        } while (randnum in myarray)

    myarray[randnum]=randnum

     }

for(x in myarray)

  printf("%d,",myarray[x])

  print

}'

结果如下

[root@x1 ~]# ./test 6 30

this programe will genrate 6 nums,between 1 to 30

5,29,9,21,25,16,



[root@x1 ~]# ./test 6 30

this programe will genrate 6 nums,between 1 to 30

8,12,22,13,3,25,



[root@x1 ~]# ./test 5 40

this programe will genrate 5 nums,between 1 to 40

4,10,21,30,33,

字符串函数

gsub(正则,替换成,要替换的)

[root@x1 ~]# awk 'BEGIN{str="ilovelinux";re="love";gsub(re,"hate",str);print str}'  

ihatelinux

[root@x1 ~]# awk 'BEGIN{str="i love linux";re="love";gsub(re,"hate",str);print str}'  #字符串有空格也可以替换

i hate linux

[root@x1 ~]# awk 'BEGIN{str="i love linux i love you";re="love";gsub(re,"hate",str);print str}'   #可以多次替换

i hate linux i hate you

[root@x1 ~]# awk 'BEGIN{str="i love linux i love you";re="love";n=gsub(re,"hate",str);print str,n}'  #gsub()返回替换的个数

i hate linux i hate you 2

index(原串,子串)  返回子串在原串中的位置

[root@x1 ~]# awk 'BEGIN{str="ilovelinux";print index(str,"love")}'

2

split(字符串,数组,分隔符)

[root@x1 ~]# awk 'BEGIN{str="i#love#linux";split(str,array,"#");for(i in array) print array[i]}'

i

love

linux

substr(字符串,起始位置,字符个数)

[root@x1 ~]# awk 'BEGIN{str="i#love#linux";print substr(str,3,4)}'

love

单词首字母大写(awk)

awk '

BEGIN {

  upper="ABCDEFGHIJKLMNOPQRSTUVWXYZ"

  lower="abcdefghijklmnopqrstuvwxyz"

  }

{position=index(lower,substr($0,1,1))

  print substr(upper,position,1)substr($0,2)

}'