How to add leading zeros for for-loop in shell? [duplicate]

Answer 1

I'm not interested in outputting it to the screen (that's what printf is mainly used for, right?) The variable $num is going to be used as a parameter for another program but let me see what I can do with this.

You can still use printf:

for num in {1..5}
do
   value=$(printf "%02d" $num)
   ... Use $value for your purposes
done