Shell Programming and Scripting

keywords.txt
world
we
are
loop it

outfile.txt
we damn world|this is it, this is it. loop it.|
let's play|how about that?|
you are good, just loop it.|Please provide few rows in each file|

expected output
we damn world|this is it, this is it. loop it.|world, we, loop it,
let's play|how about that?|
you are good, just loop it.|Please provide few rows in each file|are, loop it,

awk 'NR == FNR{a[NR] = tolower($0); n = NR; next}
  {out = $0;
  gsub("[[:punct:]]", " ", $0);
  tolower($0);
  for(i = 1; i <= n; i++)
    {if($0 ~ a[i]) out = (out a[i] ",")};
  print out}' keywords.txt outfile.txt

awk -F'|' 'FNR==NR{keys[$0];next} {for(i in keys) {if ($1~i) $0=$0 ((NF>3)? ",":OFS) i;if ($2~i) $0=$0 ((NF>3)? ",":OFS) i}}1' OFS='|' keywords.txt outfile.txt