Shell Programming and Scripting

$ grep -E 'PO##|PO  ' file[21]
file2:PO##,y
file1:PO  BOX,A

$ awk -F, 'NR==FNR{gsub(/#/," ");if($2=="y")A[$1];next}{$3="N"}FNR==1{$3="matchind"}$2=="A"{for(i in A)if(" "$1~" "i)$3="Y"}1' OFS=, file2 file1
Adrfld,category,matchind
PO  BOX,A,Y
POST,A,N
avenue,A,Y
business,X,N
bus terminus,A,Y
first cross,A,Y
firstcross,A,N

awk -F, 'NR==FNR{gsub(/#/," ");if($2=="y")A[$1];next}{$3="N,y"}FNR==1{$3="matchind,Activeflg"}$2=="A"{for(i in A)if(" "$1~" "i)$3="Y,y"}1' OFS=, file2 file1

Adrfld,category
PO BOX,A
POST,A
avenue,A
business,X
bus terminus,A
PO  BOX,A

Adrptrn,active,blankrule,cntry
ave,y,n,usa
PO#,y,y,usa
bus,y,n,usa
cross,y,n,usa
PO##,y,d,usa

Adrfld,category,matchind,active,blankrule,cntry
PO BOX,A,y,y,y,usa
POST,A,N, , , ,         
avenue,A,y,y,n,usa
business,X,N, , ,
bus terminus,A,y,y,n,usa
PO  BOX,A,y,y,d,usa

awk -F, 'NR==FNR{gsub(/#/," ");if($2=="y")A[$1]=$2FS$3FS$4;next}
         FNR==1 {$3="matching,"A["Adrptrn"]}
         $2=="A"{for(i in A)if(" "$1~" "i)$3="y,"A[i]}
         !$3    {$3="n,y, , ,"}1' OFS=, file2 file1