match index notation of file1 to the index of file2 and pull out matching rows

Question

file1 contains multiple alphabetic sequences:

AETYUIOOILAKSJ
EAYEURIOPOSIDK
RYXURIAJSKDMAO
URITORIEJAHSJD
YWQIAKSJDHFKCM
HAJSUDIDSJSIAJ
AJDHDPFDIXSIBJ
JAQIAUXCNC         


        

Answer 1

$ cat tst.awk
NR==FNR {
    lgth = length($0)
    pos2char[substr($0,1,lgth-1)] = substr($0,lgth,1)
    next
}
{
    for (pos in pos2char) {
        if ( substr($0,pos,1) == pos2char[pos] ) {
            print
            next
        }
    }
}

$ awk -f tst.awk file2 file1
AETYUIOOILAKSJ
RYXURIAJSKDMAO
URITORIEJAHSJD
JAQIAUXCNCVUFO