Question

I’ve a CSV file and I want to convert a specific column to lower case. What is the efficient way of doing this in linux?

Answer 1

awk -F"," 'BEGIN{OFS=","} {$5 = tolower($5); print}' file

to change the 5th field.

There’s also -v OFS=",", but not 100% sure how standard it is; also, quotes around , could be left out, but I kept them in for generality’s sake; so, as a variant:

awk -F, -v OFS=, '{$5 = tolower($5); print}' file

Note that awk fields are 1-based. sarathi’s answer does the same thing in perl, which is 0-based; make sure you choose the right index.

EDIT: as melpomene rightly notes, both cases only work for simple CSV without quotes or escapes.