Iterating a predefined number of times
BASH offersin {0..5}
style of loops which are
useful if you just want to iterate e.g.: 10 times and
(optionally) do something with the index variable:
for i in {0..9}; do echo "i=$i" done
Indexed for loops
If you need a proper indexed for loop where the start and stop conditions must be read from a variable, or you want the step to be different from one, you'll be happy to learn that BASH has a loop constructs which looks very similiar to C-style for-loops.
apple_array=("red" "yellow" "green")
for (( i = 0; i < ${#apple_array[@]}; i++ )); do
echo "Apple number" $i "is" ${apple_array[$i]}
done
Apple number 0 is red Apple number 1 is yellow Apple number 2 is green