shell – 如何在END之前检测awk中的最后一行

我正在尝试将最后一行添加到我正在创建的文件中.如何在END之前检测awk中文件的最后一行？我需要这样做,因为变量在END块中不起作用,
所以我试图避免使用END.

awk ' { do some things..; add a new last line into file;}'

在END之前,我不希望这样：

awk 'END{print "something new" >> "newfile.txt"}'

一种选择是使用getline函数来处理文件.它在成功时返回1,在文件末尾返回0,在出错时返回-1.

awk '
    FNR == 1 {

        ## Process first line.
        print FNR ": " $0;

        while ( getline == 1 ) {
            ## Process from second to last line.
            print FNR ": " $0;
        }

        ## Here all lines have been processed.
        print "After last line";
    }
' infile

假设有这些数据：

one
two
three
four
five

输出将是：

1: one                                                                                                                                                                                                                                       
2: two                                                                                                                                                                                                                                       
3: three
4: four
5: five
After last line