bash - I need to get the amount of numbers entered from a parameter and assign them to variables -

i making program have user provide 3 digit number when running program. if not have 3 numbers, im give error message. how can test length of number , how can assign each number out of digits variable?

thanks in advance!

i tried doing: grep '^[0-9][0-9][0-9]$' did not work.

consider following starting point. add more error checking getting practice.

#!/bin/bash  while :      read -p "enter 3 digit number or q quit: " input     if (( input >= 100 && input <= 999));          echo "good entry"         digit1=${input:0:1} && echo "digit1 $digit1"         digit2=${input:1:1} && echo "digit2 $digit2"         digit3=${input:2:1} && echo "digit3 $digit3"     elif [[ $input == "q" ]];         break     else         echo "bad entry"     fi done 

output:

enter 3 digit number or q quit: 4256 bad entry enter 3 digit number or q quit: 242 entry digit1 2 digit2 4 digit3 2 enter 3 digit number or q quit: 562 entry digit1 5 digit2 6 digit3 2 enter 3 digit number or q quit: q ###program breaks here