AWK内置变量

NR与FNR

[root@x112 linshi]# awk '{print NR}' c.txt d.txt 
1
2
3
4
5
6
7
8
[root@x112 linshi]# awk '{print FNR}' c.txt d.txt 
1
2
3
4
1
2
3
4

[root@x112 linshi]# awk 'NR==FNR{print $0}' c.txt d.txt 
1.1.1.1
2.2.2.2
3.3.3.3
4.4.4.4
[root@x112 linshi]# awk 'NR!=FNR{print $0}' c.txt d.txt 
6.6.6.6
7.7.7.7
8.8.8.8
9.9.9.9

　　

　RS与OFS

[root@x112 linshi]# awk  'BEGIN{RS="."}{print $0}' c.txt |head
1
1
1
1
2
2
2
2
3
3
[root@x112 linshi]#
[root@x112 linshi]# awk -F. 'BEGIN{OFS="------"}NR>3{print $0}{print $1,$2,$4}' c.txt
1------1------1
2------2------2
3------3------3
4.4.4.4
4------4------4

　RS指定输入换行符，OFS指定输出字段分隔符；