问一个有关sed匹配模式的话题

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

jerryjzm

回复  mr_caoke


    早就解释清楚了。


   add1, add2地址对(范围)，基本的就不说了。

我再重 ...
blackold 发表于 2010-04-12 17:19

黑哥，对于

我再重复一下。
   /an/,2p  第1行匹配/an/，地址范围为真，执行p;
第2行，匹配2, 地址范围为真, 执行p, 之后地址范围为假(重置)

这段有点不通看法，
既然是/an/,2p，   /an/是个匹配字段，那/an/ 找的行<=2时，sed 就自动将/an/到2行的内容全部p出来。
而到到/an/匹配而 >2行时，就只p出这一行了
不知我的看法是否正确。