问题描述
我想做的字符串替换以下列方式：
The output must be changed in line with the values from the reference file.
Input:
aaaa
val1=xxx
val2=yyy
val3=zzz
bbbb
val1=ppp
val2=qqq
val3=rrr
aaaa
val1=xxx
val2=yyy
val3=zzz
Reference File:
block variable value
aaaa val1 iii
aaaa val2 jjj
aaaa val3 kkk
bbbb val1 eee
bbbb val2 fff
bbbb val3 ggg
Output:
aaaa
val1=iii
val2=jjj
val3=kkk
bbbb
val1=eee
val2=fff
val3=ggg
aaaa
val1=iii
val2=jjj
val3=kkk
Currently I tried to do this using Sed command. Using which I was able to replace 1 block of code, ie,
aaaa
val1=xxx
val2=yyy
val3=zzz
into,
aaaa
val1=iii
val2=jjj
val3=kkk
The val1,val2,val3 variables occur in both the blocks 'aaaa' and 'bbbb'. But for block 'aaaa' the values will be different and for block 'bbbb' the values will be different.currently using 'sed' command I am able to replace the values for block 'aaaa', but for 'bbbb' block also the same values are being taken.
How to do a 'sed' command(or any other string replacement command) for a particular set of lines alone? My reqirement is, the control must check for the block names and then fetch the relavant values for the variables from the reference file.
It would be of great help if someone can give me a solution.
Your question ought to be edited. I am ignoring all of it except "How to do a 'sed' command(or any other string replacement command) for a particular set of lines alone?" which seems to be the heart of the question.
sed accepts addresses. To specify specific lines by line number:
sed -e '4,6s/foo/bar/'
will replace the first instance of 'foo' with 'bar', but only on line 4 to 6.
sed -e '/baz/s/foo/bar/'
will do the replacement only on lines that match the pattern 'baz'.
sed -e '/baz/{/qux/s/foo/bar/; }'
will do the replacement only on lines that match the pattern 'baz' and the pattern 'qux'.
There are many ways to specify the lines on which you wish to execute a sed command. Reading the documentation may help. (ie man sed). In other words, RTFM.
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