替换文本中的段落

Question

如何使用shell命令（sed或awk）替换文件中的段落，如下所示：

bala bala ba1
balabala.
leave me here.

this paragraph
yes, I'm going
to be replaced

The rest contains
should not be replaced.

更换后：

bala bala ba1
balaba.
leave me here.

New contains,
I'm replacement!

The rest contains
should not be replaced.

我声明原始文件包含在变量$OLD中，而new包含在另一个变量$NEW中。

Answer 1

假设您有包含新旧段落的变量，如

$ echo "$old"
this paragraph
yes, I'm going
to be replaced

和

$ echo "$new"
New contains,
I'm replacement!

您可以将文件（假设它被称为infile）读入Bash变量并使用参数扩展：

$ contents=$(< infile)
$ echo "${contents/$old/$new}"
bala bala ba1
balabala.
leave me here.

New contains,
I'm replacement!

The rest contains
should not be replaced.

要就地更改文件：

echo "${contents/$old/$new}" > infile.tmp && mv infile.tmp infile