process.sh

#!/bin/bash

RED='\033[0;31m'
YELLOW='\033[1;33m'
NC='\033[0m'

CONTINUE_PROCESSING=true

while $CONTINUE_PROCESSING; do
  # Read the next line to process
  line=$(head -n 1 files/queue.txt)
  if [ ${#line} -gt 0 ]; then
    # Remove the line from the queue
    sed -i.bak '1d' files/queue.txt

    printf "${YELLOW} processing $line ${NC}\n"

    # Your download here

    # Flag the line as complete
    echo $line >> files/complete.txt
  else
    CONTINUE_PROCESSING=false
    printf "${RED} processing complete ${NC}\n"
  fi
done