Shell Read File line by line

#save the next shell as readfile.sh
 #======================================

#!/usr/bin/bash
filename="$1"
while IFS= read -r line || [[ -n "$line" ]]; do
  # Do what you want to $line
  echo "Text read from file: $line"
done < "${filename}"
#======================================ref: https://stackoverflow.com/questions/10929453/read-a-file-line-by-line-assigning-the-value-to-a-variable

chmod +X readfile.sh

./readfile.sh  test.txt