sed匹配问题

borefo

1. 
   
2. linux-svy2:/opt/sed # cat example
   
3. The honeysuckle band played all night long for only $90.
   
4. It was an evening of splendid music and company.
   
5. Too of bad the disco floor fell through at 23:00.
   
6. The local nurse Miss P.Neave was in attendance.
   

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执行下面为什么会有下面结果？

1. 
   
2. linux-svy2:/opt/sed # sed -n '1, /\$90/p' example
   
3. The honeysuckle band played all night long for only $90.
   
4. It was an evening of splendid music and company.
   
5. Too of bad the disco floor fell through at 23:00.
   
6. The local nurse Miss P.Neave was in attendance.
   

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按照我的理解，应该只打印第一行，为什么全部打印出来了呢？

zzy7186

学习了 呵呵

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.

实例：
http://bbs.chinaunix.net/viewthr ... ;page=7#pid12057544

ghostvic

学习了 ，平时不注意还真不清楚

nxlinux

学习了

mr_caoke

回复 9# sosodream


    佩服老兄

beyondfly

试了一下，因为你的第1行和$90是同一行，第1行是肯定要打出来的，而$90是从第2行开始查找，结果直到最后也没 ...
jy02107028 发表于 2010-07-19 16:19

   哥们解释得很详细，明白了

wild_li

要第一行为啥不行sed -n '1p' file

jy02107028

试了一下，因为你的第1行和$90是同一行，第1行是肯定要打出来的，而$90是从第2行开始查找，结果直到最后也没找到，因此全部打出来了

sosodream

If the second address is a REGEXP, then checking for the ending
match will start with the line _following_ the line which matched the
first address: a range will always span at least two lines (except of
course if the input stream ends).

（节选info sed)

当第二段地址为正则时，第二段地址的匹配从第一个地址生效“下一行”为起始

用楼主的例子还说，就是，1匹配了第一行，但/\$90/是从第二行开始匹配的

解决的方法：
1改成0


说明：
`0,/REGEXP/'
     A line number of `0' can be used in an address specification like
     `0,/REGEXP/' so that `sed' will try to match REGEXP in the first
     input line too.  In other words, `0,/REGEXP/' is similar to
     `1,/REGEXP/', except that if ADDR2 matches the very first line of
     input the `0,/REGEXP/' form will consider it to end the range,
     whereas the `1,/REGEXP/' form will match the beginning of its
     range and hence make the range span up to the _second_ occurrence
     of the regular expression.