1、测试数据
[root@centos7 test]# cat a.txt 1 2 3 4 5 6 7 8 9
2、 数字的作用相当于print？
[root@centos7 test]# cat a.txt 1 2 3 4 5 6 7 8 9 [root@centos7 test]# awk ‘{if(NR == 1) {$1 = "a"} else if(NR == 2) {$1 = "b"} else {$1 = "c"}}1‘ a.txt a 2 3 b 5 6 c 8 9 [root@centos7 test]# awk ‘{if(NR == 1) {$1 = "a"} else if(NR == 2) {$1 = "b"} else {$1 = "c"}}‘ a.txt [root@centos7 test]# awk ‘{if(NR == 1) {$1 = "a"} else if(NR == 2) {$1 = "b"} else {$1 = "c"} {print $0}}‘ a.txt a 2 3 b 5 6 c 8 9
3、
[root@centos7 test]# cat a.txt 1 2 3 4 5 6 7 8 9 [root@centos7 test]# awk ‘{if(NR == 1) $1 = "a"; else if(NR ==2) $1 = "b"; else $1 = "c"}‘ a.txt [root@centos7 test]# awk ‘{if(NR == 1) $1 = "a"; else if(NR ==2) $1 = "b"; else $1 = "c"}1‘ a.txt a 2 3 b 5 6 c 8 9