Step 1: Backup the flights.csv
cp flights.csv flights.org

Step 2: Copy new data extracted from the original file
cp monthly/2022-01.csv .

Step 3: Remove ^M by pressing Ctrl+v + Ctrl+m
sed -i 's/^M$//' 2022-01.csv

Step 3: Remove Time from FL_DATE attributes (2022)
sed -i 's/ 12:00:00 AM//' flight_2022.csv

Step 4: Remove the header
sed -i 1d 2022-01.csv

Step 5: Append the flights data with the new month data 
cat 2022-01.csv >> flights.csv

SED REFERENCE
https://www.commandlinefu.com/commands/view/3802/to-print-a-specific-line-from-a-file

Remove , at the end of every line
=================================
sed 's/[,]$//' flights2016.csv > 2016.csv &
sed 's/[,]$//' flights2017.csv > 2017.csv &
sed 's/[,]$//' flights2018.csv > 2018.csv &
sed 's/[,]$//' flights2019.csv > 2019.csv &
sed 's/[,]$//' flights2020.csv > 2020.csv &
sed 's/[,]$//' flights2021.csv > 2021.csv &



CONVERT OLD DATA TO NEW FORMAT
==============================
1. Convert DATE FORMAT 2022-01-15 -> 01/15/2022 12:00:00 AM
sed -i -E 's,([0-9]{4})-([0-9]{2})-([0-9]{2}),\2/\3/\1 12:00:00 AM,g' 2015.csv
sed -i -E 's,([0-9]{4})-([0-9]{2})-([0-9]{2}),\2/\3/\1 12:00:00 AM,g' 2016.csv
sed -i -E 's,([0-9]{4})-([0-9]{2})-([0-9]{2}),\2/\3/\1 12:00:00 AM,g' 2017.csv
sed -i -E 's,([0-9]{4})-([0-9]{2})-([0-9]{2}),\2/\3/\1 12:00:00 AM,g' 2018.csv
sed -i -E 's,([0-9]{4})-([0-9]{2})-([0-9]{2}),\2/\3/\1 12:00:00 AM,g' 2019.csv
sed -i -E 's,([0-9]{4})-([0-9]{2})-([0-9]{2}),\2/\3/\1 12:00:00 AM,g' 2020.csv
sed -i -E 's,([0-9]{4})-([0-9]{2})-([0-9]{2}),\2/\3/\1 12:00:00 AM,g' 2021.csv
2. Remove , at the end of every line
sed -i 's/[,]$//' 2015.csv
sed -i 's/[,]$//' 2016.csv
sed -i 's/[,]$//' 2017.csv
sed -i 's/[,]$//' 2018.csv
sed -i 's/[,]$//' 2019.csv
sed -i 's/[,]$//' 2020.csv
sed -i 's/[,]$//' 2021.csv



COMBINE ALL YEARS
=================
sed 1d flights2016.csv > 2016.csv &
sed 1d flights2017.csv > 2017.csv &
sed 1d flights2018.csv > 2018.csv &
sed 1d flights2019.csv > 2019.csv &
sed 1d flights2020.csv > 2020.csv &
sed 1d flights2021.csv > 2021.csv &

cp flights2015.csv flights2.csv
cat 2016.csv >> flights2.csv
cat 2017.csv >> flights2.csv
cat 2018.csv >> flights2.csv
cat 2019.csv >> flights2.csv
cat 2020.csv >> flights2.csv
cat 2021.csv >> flights2.csv

sed 1d flights2022.csv > 2022.csv
cp flights2.csv flights3.csv
cat 2022.csv >> flights3.csv










Step 1: Remove ^M from the end of line and add , to the end of line (Press Ctrl+v and Ctrl+m)
sed -i 's/^M$/,/' monthly/2022-01.csv

Step 2: Append flights.csv with the new data
./addmonth 2022-01.csv flights2.csv

cp monthly/$1 .
sed -i 's/^M$/,/' $1
sed -i 1d $1
cat $1 >> $2

# Add text 'XXXX' at the end of every line
sed -n 's/$/XXXX/' input.txt > output.txt
sed 's/$/,/' 2022-01.csv > 2022-01n.csv
sed 's/^M$/,/' 2022-01.csv > 2022-01n.csv
Press Ctrl+v and Ctrl+m

s/source/destination/

# Remove the last character of each line
# https://www.cyberciti.biz/faq/sed-remove-last-character-from-each-line/
sed 's/.$//' flights.temp > flights2.csv &
sed 's/[,]$//' flights.temp > flights2.csv &

# By default, sed command so far used would remove any last character. But, say you can restrict removal to digits only as follows:
echo "I love Pizza6" | sed 's/[0-9]$//'
echo "The best blog in Unixverse3" | sed 's/[[:digit:]]$//'
echo "I love Pizza6Times" | sed 's/[0-9]$//'

# The “[0-9]“/”[[:digit:]]” indicates all digits such as 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. Similarly, we can use the following to delete all alphabets:
echo "I love donuts two times a dayz" | sed 's/[[:alpha:]]$//'
echo "I love donuts 2 times a dayZ" | sed 's/[[:upper:]]$//'