sed替换匹配关键字下面的指定行的内容

飘动de心

需要处理的文件如下：
[root@test ~]# cat 11
[1]
1=1
2=2
3=3
[2]
1=1
4=4
2=2
3=3
[3]
1=1
2=1
3=1

需要替换[2]下的2=2等于2=4..

根据先匹配后替换的原则，sed '/\[2\]/{n;n;n;s/2=.*/2=y/}' 11初步实现，但要指定行数
如何不指定关键字后第3行这种方式实现？比如找到匹配行到文件末尾，替换一次这样的方式

moperyblue

1. sed '/2]/{:a;N;s/2=.*/2=y/;t;ba}'

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1. sed '/2]/{:a;N;/2=.*/!ba;s//2=y/}'

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[1]
1=1
2=2
3=3
[2]
1=1
4=4
2=y
3=3
[3]
1=1
2=1
3=1

elu_ligao

1. sed '/\[2\]/{:a N;s/2=2/AAAAAA/;Ta}'

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飘动de心

核心部分果然没明白，用了标签么？
sed '/2]/{:a;N;s/2=.*/2=y/;t;ba}'
回复 2# moperyblue

飘动de心

不会的部分能解释下么，:a是指标签么
sed '/\[2\]/{:a N;s/2=2/AAAAAA/;Ta}'
回复 3# elu_ligao

moperyblue

回复 4# 飘动de心


info sed
=>

`: LABEL'
     [No addresses allowed.]

     Specify the location of LABEL for branch commands.  In all other
     respects, a no-op.

`b LABEL'
     Unconditionally branch to LABEL.  The LABEL may be omitted, in
     which case the next cycle is started.

`t LABEL'
     Branch to LABEL only if there has been a successful `s'ubstitution
     since the last input line was read or conditional branch was taken.
     The LABEL may be omitted, in which case the next cycle is started.

`T LABEL'
     Branch to LABEL only if there have been no successful
     `s'ubstitutions since the last input line was read or conditional
     branch was taken. The LABEL may be omitted, in which case the next
     cycle is started.

1. sed '/2]/,/2=/{s/2=.*/2=y/}'

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moperyblue

1. awk '/\[2]/{f=1}f{if(/2=/){$0="2=y";f=0}}1'

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jason680

回复 1# 飘动de心


$ awk -vseg="2" -vorg="2=2" -vnew="2=4" 'match($0,"^[[]([^]]+)",a){s=a[1]}s==seg&&org==$0{$0=new}1' 11
[1]
1=1
2=2
3=3
[2]
1=1
4=4
2=4
3=3
[3]
1=1
2=1
3=1

sunzhiguolu

1. perl -nle 'if(/\A\[2/){$S=1}if($S && /\A(2=)2/){$S=1;print $1,4;next}print' f

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[1]
1=1
2=2
3=3
[2]
1=1
4=4
2=4
3=3
[3]
1=1
2=1
3=1

jcdiy0601

1. sed -r '/\[2\]/{:a;N;/2=2/s/2=2/2=4/;ba}' file

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