Shell Programming and Scripting

for i in {A..Z}{A..Z}{A..Z}{A..Z};do mkdir $i;done

for ((i = 0; i <= 9; i++))
do
  for((j = 0; j <= 9; j++))
  do
    for((k = 0; k <= 9; k++))
    do
      for((l = 0; l <= 9; l++))
      do
        for((m = 1; m <= 9; m++))
        do
          mkdir "$i$j$k$l$m" #This will create the folders
        done
      done
    done
  done
done

printf "%04d\n" $(seq 0 9999) | xargs -I{} mkdir {}

$ cat filename.pl
for (AAAA..ZZZZ)  {
    mkdir $_;    
}

$ perl filename.pl