How to increment a zero padded int in Bash

Question

I have a set of records to loop. The numbers range from 0000001 to 0089543 that ill call UIDX.

if i try something like:

for ((i=0; i< 0089543; i++)); do
    ((UIDX++))
done

counter increments 1, 2, 3, 4 as opposed to the 0000001, 0000002... that i need.

what is the best way to pad those leading zero's?

Answer 1

Use the printf command to format the numbers with leading zeroes, eg:

for ((i = 0; i < 99; ++i)); do printf -v num '%07d' $i; echo $num; done

From man bash:

printf [-v var] format [arguments]
Write the formatted arguments to the standard output under the control of the format. The -v option causes the output to be assigned to the variable var rather than being printed to the standard output.