Append List of lines, it will check in input file and if it not exists then it will append .

AppendIfnotExists.sh

function AppendIfnotExists() {
 while read s
 do
  inputFile="$2"
  
  # if starting content matched then comment them
  local startStr=$( echo "${s}" | cut -d" " -f1 )
  
  grep -q "^#${s}" $inputFile || sed -i "s/^$startStr/#$startStr/g" $inputFile
  
  if ! grep "^${s}" $inputFile >/dev/null 2>&1; then
    echo "${s}" >> $inputFile
  fi
  done <<< "$1"
 
}