如果模式匹配，则删除行，除非行包含字符串

Question

如果匹配模式xxx，则应删除文本文件中的所有行，除非该行包含yyy。

示例输入（文字）：

- 1 The first line does not contain the pattern.
- 2 The second line does contain the pattern xxx but still can't be deleted because of yyy.
- 3 The third line should be remove because it only contains xxx.

所需的输出（文字）：

 
- 1 The first line does not contain the pattern.
- 2 The second line does contain the pattern xxx but still can't be deleted because of yyy.

Answer 1

这应该有效（未经测试）

 awk '!/xxx/ || /yyy/'

Answer 2

如果行号是输入/输出的一部分

$ awk '!/xxx/ || /yyy/ {$1=++c;print}' lines

1 This first line does not contain the pattern.
2 This second line does contain the pattern xxx but still can't be deleted because of yyy.

如果不需要行号，请使用@ rici的解决方案