linux - 使用 BASH 从一行中取出最后一个单词并将其添加到开头

Question

我们有一个要求，我们的文本文件的内容是这样的:

[some-section-1]
big_msg_line1   var=random_value1
big_msg_line2   var=random_value2
big_msg_line3   var=random_value3

[some-section-2]
"lots of irrelevant data"

[some-section-3]
"lots of irrelevant data"

[some-section-4]
big_msg_line4   var=random_value4
big_msg_line5   var=random_value5
big_msg_line6   var=random_value6
big_msg_line7   var=random_value7
big_msg_line8   var=random_value8

[some-section-5]
"lots of irrelevant data"

我们要修改的所有行都以公共(public)字符开头，就像在这个例子中我们要修改的所有行都以单词“big”开头。我们想把它改成这样:

[some-section-1]
random_value1   msg=big_msg_line1
random_value2   msg=big_msg_line2
random_value3   msg=big_msg_line3

[some-section-2]
"lots of irrelevant data"

[some-section-3]
"lots of irrelevant data"

[some-section-4]
random_value4   msg=big_msg_line4
random_value5   msg=big_msg_line5
random_value6   msg=big_msg_line6
random_value7   msg=big_msg_line7
random_value8   msg=big_msg_line8

[some-section-5]
"lots of irrelevant data"

这些仅供引用。原始文件包含的数据比这些多得多。成百上千行。

我目前正在使用 for 循环执行此操作，读取每一行，剪切值，按照我想要的方式格式化它们，然后放入单独的文件中，然后用新文件替换原始文件。有没有办法使用一些衬里来实现这一目标？那真的会有很大的帮助。希望我的问题很清楚。

提前致谢。

Answer 1

据我所知，这个 awk 单行代码可以完成这项工作:

cat a
[some-section-1]
big_msg_line1   var=random_value1
big_msg_line2   var=random_value2
big_msg_line3   var=random_value3

[some-section-2]
lots of irrelevant data

[some-section-3]
lots of irrelevant data

[some-section-4]
big_msg_line4   var=random_value4
big_msg_line5   var=random_value5
big_msg_line6   var=random_value6
big_msg_line7   var=random_value7
big_msg_line8   var=random_value8

[some-section-5]
lots of irrelevant data 

这个:

awk '{FS="var="; if ($1~/big/) { print $2"\tmsg="$1} else {print }}' a

给予

[some-section-1]
random_value1   msg=big_msg_line1   
random_value2   msg=big_msg_line2   
random_value3   msg=big_msg_line3   

[some-section-2]
lots of irrelevant data

[some-section-3]
lots of irrelevant data

[some-section-4]
random_value4   msg=big_msg_line4   
random_value5   msg=big_msg_line5   
random_value6   msg=big_msg_line6   
random_value7   msg=big_msg_line7   
random_value8   msg=big_msg_line8   

[some-section-5]
lots of irrelevant data