unix 1 liner to process a CSV

Recently I needed to inspect a CSV. I could open it in a spreadsheet and try hiding columns, or write a quick unix 1 liner. The one-liner is shown below in a code block.

cat out.csv | tac | cut -d , -f 3,5 | less

This one-liner uses four different commands, cat, tac, cut, and less, which each modify the data in a specific way. Lets go through them one by one.

1. cat out.csv reads the file out.csv. The real file was larger, but here’s a small example

A,B,C,D,E,F
197,198,X,45.07,5418377,0.0006699515234523945
196,197,Y,45.07,8791092,0.0010869685660872541
198,199,Z,42.99,30896590,0.001540929478413
194,195,A1,52.5,598682,0.0016263458559409028
195,196,B1,47.72,18092026,0.006921275128414672
193,194,C1,52.68,2773168,0.008094877815466361
178,179,D1,63.42,103698,0.017121157657426167
192,193,E1,52.69,7046310,0.0206503955280557
175,176,F1,66.03,73040,0.029825968985690565

2. tac is the opposite of cat, it prints the input in reverse order line by line.

175,176,F1,66.03,73040,0.029825968985690565
192,193,E1,52…