ETL Transformation Example: Handling Missing Values and Data

# ***                                                 *** #
# *** Issue #3 - Get rid of all rows with null values *** #
# ***                                                 *** #  
echo -e "\nTask #3 - Searching for Null Values"
extract_nulls(){
    # Create an empty file called null_values.txt
    > null_values.txt
    # extract all lines with "null" and append to the file
    cat raw_data.csv | grep null >> null_values.txt
}
extract_nulls
delete_nulls(){
    if [ -s null_values.txt ]
    then
        echo -e "\nFound Null Values:"
        cat null_values.txt
        # Grab the dates of lines
        null_dates=$(cut --delimiter "|" --fields 1 null_values.txt)
        echo -e "\nRemoving Null Values..."
        # Remove all rows with null dates from raw_data.csv
        grep -v "$null_dates" raw_data.csv > temp.csv; mv temp.csv raw_data.csv
        echo -e "Done."
    else
        echo "There Are No Null Values"
    fi
}
delete_nulls