Linux variable expansion problem ？

Question

I'd like to get a sequence of number like this 01,02,..,30 But if I use {01..30}, I will get 1,2,..30, the zero before single-digit number is missing. How can I get the format like 01,02..30 ? Thanks in advance

Answer 1

In Bash4, your {01..30} brace expansion actually works as you want it to. If you are on Bash3 or lower you can use the printf builtin along with the brace expansion to get what you want without resorting to external commands.

$ printf "%02d " {1..20}
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20

Answer 2

seq -w 1 30  # ought to work

as in:

for number in $(seq -w 1 30); do
 touch /tmp/bleah$number.dat
done