match target row with sed or grep - bash

Question

I want to catch the row contain "Will_Liu>" from massive_data.txt if the n < m or n==0 or m==0, a period of the prototype is as below.
cat massive_data.txt
Will_Liu> set Name.* xxx
============================================
Id Name Para status
============================================
1 name-1 xxxxx OK
2 name-2 xxxxx OK
3 name-3 xxxxx Not_OK
. ... .... OK
. ... .... OK
m name-m .... Not_OK
============================================
Total: m name attempted, n name set OK
In the above code, the "m" and "n" are variable, if the n < m or n==0 or m==0, print the rows contain "Will_Liu>" ;
if n==m and both of them !=0, just skip and ignore this situation.
I just could use "grep" and "sed" to grasp key points like those:
cat test.txt
Will_Liu> set Name_group1 xxx
============================================
Id Name Para status
============================================
1 name-1 xxxxx OK
2 name-2 xxxxx OK
3 name-3 xxxxx Not_OK
============================================
Total: 3 name attempted, 2 name set OK
Will_Liu> set Name_group2 yyy
============================================
Id Name Para status
============================================
1 name-4 xxxxx OK
2 name-5 xxxxx Not_OK
3 name-6 xxxxx Not_OK
============================================
Total: 3 name attempted, 1 name set OK
I could use "sed" and "grep" command like this:
sed -n "/Total: 3 name attempted,/p" test.txt
Total: 3 name attempted, 2 name set OK
Total: 3 name attempted, 1 name set OK
grep -B 9 "Total: 3 name attempted" test.txt | sed -n '/Will_Liu>/p'
Will_Liu> set Name_group1 xxx
Will_Liu> set Name_group2 yyy
in the grep command the 9 is 3+6, the 6 is base on the format of the structure, it's a fixed value.
So how can I introduce 2 variates to define the "m" and "n" and improve my code to get expected result from massive_data.txt?
My expect output:
Will_Liu> set Name1 xxx
Will_Liu> set Name2 yyy
Will_Liu> set Name3 zzz
. . .
. . .
. . .

Answer 1

In general, any previous line you want to print matches another pattern. In these cases it is better to store the last candidate to be printed and when you reach your condition, decide what to do with it. For example
awk '/^Will_Liu/{
last_will=$0
}
/^Total/{
m=$2; n=$5
if (m>n || (m==0 && n==0))
print last_will
}' file
In cases where you really don't have any pattern to select the last candidate to print, and you have to decide some line number to print after a math operation on matched line data, then you could double pass a file, or use tac to invert the input or keep all last lines in a hash array or any similar approach. These approaches could be not efficient sometimes. For example, with storing all lines, which is not recommended for your case
awk '{ line[NR]=$0 }
/^Total/{
m=$2; n=$5
if (m>n || (m==0 && n==0))
print line[NR-(m+5)]
}' file