UNIX for Dummies Questions & Answers

File1
a,1,2,b,c,d,e,USA
q,3,4,w,e,r,t,CAN

File2
t,y,u,i,o,1,2,5
v,b,n,m,h,3,4,9
a,s,d,f,g,h,j,7

t,y,u,i,o,1,2,5,USA - since the 6th and 7th field of file2 is = to 2th and 3rd of file1 it append the last field USA
v,b,n,m,h,3,4,9,CAN - since the 6th and 7th field of file2 is = to 2th and 3rd of file1 it append the last field CAN

a,s,d,f,g,h,j,7 - the 6th and 7th field of file2 is NOT EQUAL to 2th and 3rd of file1 it will only retain the display of records.

Awk -F, 'FNR==NR {A [$2 FS $3]=$7; NEXT}($6 FS $7 in A )

awk -F, 'FNR==NR {A[$2 FS $3]=$7; next}(($6 FS $7) in A)'

awk -F, '
FNR == NR {
        A[$2 FS $3] = $8
        next
}       
{       x = $6 FS $7
        if(x in A) $9 = A[x]
        print
}' OFS=, File1 File2

t,y,u,i,o,1,2,5,USA
v,b,n,m,h,3,4,9,CAN
a,s,d,f,g,h,j,7