How do I extract column from CSV with quoted commas, using the shell?

Question

I have a CSV file, but unlike in related questions, it has some columns containing double-quoted strings with commas, e.g.

foo,bar,baz,quux
11,\"first line, seco         


        

Answer 1

Here is a quick and dirty Python csvcut. The Python csv library already knows everything about various CSV dialects etc so you just need a thin wrapper.

The first argument should express the index of the field you wish to extract, like

csvcut 3 sample.csv

to extract the third column from the (possibly, quoted etc) CSV file sample.csv.

#!/usr/bin/env python3

import csv
import sys

writer=csv.writer(sys.stdout)
# Python indexing is zero-based
col = 1+int(sys.argv[1])
for input in sys.argv[2:]:
    with open(input) as handle:
        for row in csv.reader(handle): 
            writer.writerow(row[col])

To do: error handling, extraction of multiple columns. (Not hard per se; use row[2:5] to extract columns 3, 4, and 5; but I'm too lazy to write a proper command-line argument parser.)