// generowanie pliku songs.csv
awk -F'<SEP>' '{print $2","$3","$4}' unique_tracks.txt > temp_songs.csv
sort -u -t, -k1,1 temp_songs.csv > songs.csv
rm temp_songs.csv

// generowanie pliku unique_tracks.csv
awk -F'<SEP>' '{print $1","$2","$3}' triplets_sample_20p.txt > triplets.csv

// generowanie pliku dates.csv
awk -F, '{OFS=","; $4=strftime("%m", $3); print $3","$4}' triplets.csv > temp_dates.csv
sort -n -u -t, -k1,1 temp_dates.csv > dates.csv
rm temp_dates.csv