This can be done easily in one line:

echo "RAM,SWAP" > stats.csv && tegrastats | while read a; do echo "$a" | awk -F "[/ ]" '{OFS=","}{print $2,$7}' >> stats.csv; done

will stream RAM and SWAP usage to a comma-delimited CSV file named stats.csv with column headers in the first row structured like this:

RAM,SWAP

2209,100

2214,100

2214,100

2214,100

2214,100

2214,100

2214,100

You can adapt this easily to your needs by adding additional column headers in the echo part and extracting said columns in the print part.

A little explanation:

- The $2 in the print part extracts the second column from tegrastats

- The -F "[/ ]" makes sure to segment the output by spaces and forward-slashes

- The while read loop is for unbuffering the output from tegrastats

- To follow the transformation execute the first row in this post in one terminal, open another terminal and enter tail -f stats.csv (in the same directory) to see the output streaming into the stats.csv file

Cheers