新手关于sed的初级问题

lox

新手，刚开始学习shell，今天看了zhy版主的sed，很多地方不明白，希望大家帮忙解释一下，万分感谢！
zhy中的一段程序：

（1）
zhyfly@zhyfly:~/bash$ sed -e '=' test.txt
1
The honeysuckle band played all night long for only $90.
2
It was an evening of splendid music and company.
3
Too bad the disco floor fell through at 23:00.
（2）
zhyfly@zhyfly:~/bash$ sed -e '=' test.txt
1
The honeysuckle band played all night long for only $90.
2
It was an evening of splendid music and company.
3
Too bad the disco floor fell through at 23:00.
4
The local nurse Miss P.Neave was in attendance.
（3）
zhyfly@zhyfly:~/bash$ sed -n -e '=' test.txt
1
2
3
4
（4）
zhyfly@zhyfly:~/bash$ sed -n -e '/music/p' test.txt
It was an evening of splendid music and company.
（5）
zhyfly@zhyfly:~/bash$ sed -n -e '/music/=' test.txt
2
zhyfly@zhyfly:~/bash$ sed -n -e '/music/p' -e '/music/=' test.txt
It was an evening of splendid music and company.
2
（6）
zhyfly@zhyfly:~/bash$ sed -e '=;p' test.txt
1
The honeysuckle band played all night long for only $90.
The honeysuckle band played all night long for only $90.
2
It was an evening of splendid music and company.
It was an evening of splendid music and company.
3
Too bad the disco floor fell through at 23:00.
Too bad the disco floor fell through at 23:00.
4
The local nurse Miss P.Neave was in attendance.
The local nurse Miss P.Neave was in attendance.
（7）
zhyfly@zhyfly:~/bash$ sed -n -e '=;p' test.txt
1
The honeysuckle band played all night long for only $90.
2
It was an evening of splendid music and company.
3
Too bad the disco floor fell through at 23:00.
4
The local nurse Miss P.Neave was in attendance.
（8）
zhyfly@zhyfly:~/bash$ sed -n -e '=' -e 'p' test.txt
1
The honeysuckle band played all night long for only $90.
2
It was an evening of splendid music and company.
3
Too bad the disco floor fell through at 23:00.
4
The local nurse Miss P.Neave was in attendance.
zhyfly@zhyfly:~/bash$

前面四个还明白，到了第五个就不明白了，大家给解释下，谢~

lox

第8个，-e选项允许在同一行里执行多条命令，
第8个的意思是给每行加行号码并且输出每行。
其他的三个谁给解释一下阿？

lox

呵呵，第6，7个明白了，就剩下第5个有点不懂了。根据zhy老大的理论，
多个命令常用的方法
主要有
a.利用多个-e选项
b.利用 ；
c.使用脚本文件
上面几种方法，前面也有提到。
可以理解第6，7个。
只剩下一个了。