sed中N，sed and awk 2Nd Edition问题三

davidbreathe

hi,最近在看sed&awk第二版本，第6.1.1中有一个例子，如下：

cat testfile6
Consult Section 3.1 in the Owner and Operator
Guide for a description of the tape drives
available on your system.
Look in the Owner and Operator Guide shipped with your system.
Two manuals are provided including the Owner and
Operator Guide and the User Guide.
The Owner and Operator Guide is shipped with your system.

目的：要将文本中出现的所有跨行或不跨行的 Owner and Operator Guide替换成Installation Guide

我写的语句：
sed "/Owner/ {N;s/Owner *\n*and *\n*Operator *\n*Guide/Installation Guide\n/g}" testfile6   

结果是只将第一、二处替换成功，第三、四处没有替换。结果如下：
Consult Section 3.1 in the Installation Guide
for a description of the tape drives
available on your system.
Look in the Installation Guide
shipped with your system.
Two manuals are provided including the Owner and
Operator Guide and the User Guide.
The Owner and Operator Guide is shipped with your system.

请问原因是？

yestreenstars

因为你的脚本每次只处理两行

yestreenstars

这个效果如何？

1. $ sed -r ':1;N;$!b1;s/Owner\s+and\s+Operator\s+Guide/Installation Guide/g' i
   
2. Consult Section 3.1 in the Installation Guide for a description of the tape drives
   
3. available on your system.
   
4. Look in the Installation Guide shipped with your system.
   
5. Two manuals are provided including the Installation Guide and the User Guide.
   
6. The Installation Guide is shipped with your system.

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1. $ perl -pe 'BEGIN{$/=undef};s/Owner\s+and\s+Operator\s+Guide/Installation Guide/g' i
   
2. Consult Section 3.1 in the Installation Guide for a description of the tape drives
   
3. available on your system.
   
4. Look in the Installation Guide shipped with your system.
   
5. Two manuals are provided including the Installation Guide and the User Guide.
   
6. The Installation Guide is shipped with your system.

复制代码

runintostar

回复 1# davidbreathe
第三个：
因为使用N读入下一个inputline后，下一次再读就读不到这一行了，就是每一行只会读一次，这么说楼主明白了吧
第四个：
已经到最后一行了，后面已经无记录，N执行失败了，后面的代码不执行

   

davidbreathe

回复 4# runintostar

呀，明白了，多谢多谢。那这么说书上有错哎


   

elu_ligao

1. sed '/Owner/{$!N;s/Owner *\n*and *\n*Operator\( *\n*Guide\)/Installation\1/g;P;D}'

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