open IN ,"a.txt" or die $!; ##读入文件
open OUT ,">b.txt" or die $!; ##输出文件
while (<IN>) {
print OUT $_;
if ($_ =~ /add/){print OUT "xxx\n"
}
}
[root@june2 perl]# cat a.txt
add
1
2
3
4
add
5
6
add
8
9
aaaa
bbbbb
[root@june2 perl]# perl a1.pl
[root@june2 perl]# cat b.txt
add
xxx
1
2
3
4
add
xxx
5
6
add
xxx
8
9
aaaa
bbbbb