Find a pattern and modify the next line without modifying the other contents in the file. preferably linux based commands (sed, awk etc) - linux

Question

I have a file which looks like this:
# Hello, welcome to the world
# Trying to modify XXXXXX
# Some more random text
poly RANDOM LAYER{
20 25
18 2
1 5
1 2
5 6
}
poly RANDOM LAYER{
30 50
14 25
15 25
15 26
15 26
15 27
}
I would like to increment the values in the next line of poly RANDOM layer,say add 10 to the first number (20+10=30) and 20 to the next number (25+20=45). The rest of the contents should be the same:
This should be done for all the lines immediately after poly RANDOM LAYER
The output should look like:
# Hello, welcome to the world
# Trying to modify XXXXXX
# Some more random text
poly RANDOM LAYER{
*30 45*
18 2
1 5
1 2
5 6
}
poly RANDOM LAYER{
*40 60*
14 25
15 25
15 26
15 26
15 27
}

Answer 1

If the specific leading white space is always 4 chars:
$ awk 'f{$1=" "$1+10; $2+=20; f=0} /RANDOM/{f=1} 1' file
# Hello, welcome to the world
# Trying to modify XXXXXX
# Some more random text
poly RANDOM LAYER{
30 45
18 2
1 5
1 2
5 6
}
poly RANDOM LAYER{
40 70
14 25
15 25
15 26
15 26
15 27
}
otherwise use:
$ awk 'f{fmt=$0; gsub(/[^[:space:]]+/,"%s",fmt); $0=sprintf(fmt,$1+10,$2+20); f=0} /RANDOM/{f=1} 1' file
as that will just reproduce in your output WHATEVER leading, trailing, or inter-field white space you have in your input.

Answer 2

You say (sed, awk, etc). Is perl part of etc?
perl -pe 's/(\d+)/$1+10/ge if($lastLineMatch); $lastLineMatch = m/poly RANDOM/; ' < file
Or if you want to add different values to the two numbers:
perl -pe 's/(\d+)(\D+)(\d+)/($1+10).$2.($3+20)/ge if($lastLineMatch); $lastLineMatch = m/poly RANDOM/; ' < file