复制行并替换某些行的开头

Question

我有一个包含

形式的行的文件

this is block 1
a 1 2 3
this is block 2
a 3 1 9
this is block 3
a 10 2 32
...

我想复制一些行并替换开头，使其成为：

this is block 1
a 1 2 3
b 1 2 3
c 1 2 3
this is block 2
a 3 1 9
b 3 1 9
c 3 1 9
this is block 3
a 10 2 32
b 10 2 32
c 10 2 32
...

不确定如何使用awk，sed或其他优雅选项解决此问题。

Answer 1

使用sed或awk，您可以这样做：

$ cat data 
this is block 1
a 1 2 3
this is block 2
a 3 1 9
this is block 3
a 10 2 32
$ sed -rn '/^a/{p;s/^a/b/;p;s/^b/c/;p;n};p' data 
this is block 1
a 1 2 3
b 1 2 3
c 1 2 3
this is block 2
a 3 1 9
b 3 1 9
c 3 1 9
this is block 3
a 10 2 32
b 10 2 32
c 10 2 32
$ awk '{if($1=="a") {print;$1="b";print;$1="c";print} else {print}}' data 
this is block 1
a 1 2 3
b 1 2 3
c 1 2 3
this is block 2
a 3 1 9
b 3 1 9
c 3 1 9
this is block 3
a 10 2 32
b 10 2 32
c 10 2 32
$