grep：打印两个匹配项

Question

以下命令仅返回来自file2的匹配。

grep -f file1 file2

如何从file2的第二个匹配后的第一个文件（file1）中打印匹配行？

Answer 1

awk 'NR==FNR{res[$0]; next}
{
    found = 0
    for (re in res) {
        if ($0 ~ re) {
            print "found:", re
            found = 1
        }
    }
}
found
' file1 file2