Shell Programming and Scripting

abc
der
xyz

123 abc
234  der  sgd
345 wse xyz
000 qwe qaws zksd

abc 123
der 234
xyz 345

filearray=( `cat token.txt | tr '\n' ' '`)
 
for ((i=0;i<${#filearray[*]};i++))
{
awk '{for (f=NF; f>=0 ; f--) if ($f ~/${filearray[i]}/) {print  $filearray[i], $1,; next}}' flat.txt} >> newfile.txt
exit

awk 'NR==FNR{A[$1];next}{for(i=2;i<=NF;i++){if($i in A) print $i,$1}}' token.txt flat.txt

while read TOKEN REST
  do for ((i=0; i<${#filearray[@]}; i++))   
     do     [ "$REST" != "${REST/${filearray[$i]}/}" ] && echo ${filearray[$i]} $TOKEN
     done
 done <flat.txt
abc 123
der 234
xyz 345