文件的符合SED

Question

編號，我想知道，如果sed的是能夠做一些線計算工作，而編號特定行的，假設我有

Some question 
     some answer 
     another answer 
    Another question 
     another answer 
     other answer 

我希望有一個命令文件轉換到這一點：所需的輸出

1_ Some question 
     a_ some answer 
     b_ another answer 
    2_ Another question 
     a_ another answer 
     b_ other answer 

這有可能與sed的？如果沒有，如何在沒有bash腳本解決方案的情況下完成這項工作？

Answer 1

Perl有一個方便的功能，++作品上的字符：

perl -lpe ' 
    /^\S/ and do {$inner_counter="a"; s/^/ ++${outer_counter} . "_ "/e}; 
    /^\s/ and s/^\s+/$& . ${inner_counter}++ . "_ "/e 
' file 

1_ Some question 

    a_ some answer 

    b_ another answer 

2_ Another question 

    a_ another answer 

    b_ other answer 

Answer 2

最好用awk來嘗試。我認爲要編號不與任何withespace字符開頭的行：

awk '$0 !~ /^[[:blank:]]/ { print ++i "_", $0; next } { print }' infile 

它產生：

1_ Some question 
     some answer 
     another answer 
2_ Another question 
     another answer 
     other answer