问一个有关sed匹配模式的话题

mr_caoke

我有个文件，其内容是
The honeysuckle band played all night long for only $90.
It was an evening of splendid music and company.
Too bad the disco floor fell through at 23:10.
The local nurse Miss P.Neave was in attendance.

我使用如下命令，得到如下结果

1. 
   
2. [caoke@Linux ~]$ sed -n '/It/,2'p tmp.sed
   
3. It was an evening of splendid music and company.
   

复制代码

我使用如下命令，得到如下结果

1. 
   
2. [caoke@Linux ~]$ sed -n '/an/,2'p tmp.sed
   
3. The honeysuckle band played all night long for only $90.
   
4. It was an evening of splendid music and company.
   
5. The local nurse Miss P.Neave was in attendance.
   
6. 
   
7. [color=Red]很奇怪，不是应该在第二行范围内搜索吗？[/color]
   

复制代码

这两个命令有什么区别

1. 
   
2. sed -n '/an/,2'p tmp.sed
   
3. sed -n '2,/an/'p tmp.sed
   

复制代码

不胜感激

blackold

起点和终点不同啊。

jerryjzm

[monitor@test ~]$ sed '2p' ./tmp.sed
The honeysuckle band played all night long for only $90.
It was an evening of splendid music and company.
It was an evening of splendid music and company.
Too bad the disco floor fell through at 23:10.
The local nurse Miss P.Neave was in attendance.

[monitor@test ~]$ sed -n '2p' ./tmp.sed
It was an evening of splendid music and company.

[monitor@test ~]$ sed -n '/It/p' ./tmp.sed   
It was an evening of splendid music and company.

[monitor@test ~]$ sed -n '/It/,2p' ./tmp.sed
It was an evening of splendid music and company.

[monitor@test ~]$ sed -n '/It/,2'p ./tmp.sed  
It was an evening of splendid music and company.

[monitor@test ~]$ sed -n '/It/,3p' ./tmp.sed  
It was an evening of splendid music and company.
Too bad the disco floor fell through at 23:10.

[monitor@test ~]$ sed -n '/an/p' ./tmp.sed     
The honeysuckle band played all night long for only $90.
It was an evening of splendid music and company.
The local nurse Miss P.Neave was in attendance.

[monitor@test ~]$ sed -n '/an/2p' ./tmp.sed  
sed: -e expression #1, char 5: unknown command: `2'

[monitor@test ~]$ sed -n '/an/,2p' ./tmp.sed
The honeysuckle band played all night long for only $90.
It was an evening of splendid music and company.
The local nurse Miss P.Neave was in attendance.

应该很清楚了，那就是个label

Shell_HAT

'/It/,2' 从包含It的行到第二行
'/an/,2' 从包含an的行到第二行

mr_caoke

回复 3# jerryjzm


    说实话，我还是不太明白，能不能解释下那个语句的含义

Shell_HAT

哪句还是不太明白？

mr_caoke

回复 6# Shell_HAT


    [monitor@test ~]$ sed -n '/an/,2p' ./tmp.sed
The honeysuckle band played all night long for only $90.
It was an evening of splendid music and company.
The local nurse Miss P.Neave was in attendance.


拿这个来说吧，从an到第2行。但是为什么第3行也被选进来了？

blackold

回复 7# mr_caoke


不是第三行，是第四行。

因为匹配了两个范围。

nuclearxin

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.

mr_caoke

回复 8# blackold


    这句话的意思难道是匹配第2行，或者匹配an，的所有行？？？？？？？？？