sed的模板确定范围内的被打印无法理解

Shell_HAT

地址范围的right operand是pattern的时候：
http://bbs.chinaunix.net/viewthread.php?tid=1689518#pid12055900

range operator maintains its own Boolean state.
It is false as long as its left operand is false. Once the left operand is true, the range operator stays true until the right operand is true, after which the range operator becomes false again.
The operator doesn't become false until the next time it is evaluated.

Shell_HAT

回复 4# 木木老蔫


    对于/a/来说是第二轮

Shell_HAT

回复 6# 木木老蔫


第一行：/a/中
从第二行开始，判断/b/，中
从第三行开始，判断/a/，不中