I saw the following code in Bash shell Decimal to Binary conversion and I was wondering how it works? I tried googling with no avail.
D2B=({0..1}{0..1}{0..1}{0..1}{0..1}{0..1}{0..1}{0..1})
echo ${D2B[7]}
What does the code above do?
{N..M}, for integer literals N and M, generates the series of integers from N to M, inclusively, separated by spaces. This is called a "brace expansion", and is a bashism. As you can see, all brace expansions are done before adding spaces between them.
variable=({some expansion}) puts each of the expanded items in an array, and ${variable[index number]} extracts the value at that index. So your code effectively returns the number seven in binary string form.