split

#!/bin/bash

STR="Sarah,Lisa,Jack,Rahul,Johnson" #String with names
IFS=',' read -ra NAMES <<< "$STR" #Convert string to array

#Print all names from array
for name in "${NAMES[@]}"; do
  echo $name
done

#Print index from array
for name in "${!NAMES[@]}"; do
  echo $name
done

ref: https://tecadmin.net/split-a-string-on-a-delimiter-in-bash-script/