Extract specific columns from delimited file using Awk

Question

Sorry if this is too basic. I have a csv file where the columns have a header row (v1, v2, etc.). I understand that to extract columns 1 and 2, I have to do: awk -F "," '{print $1 "," $2}' infile.csv > outfile.csv. But what if I have to extract, say, columns 1 to 10, 20 to 25, and 30, 33? As an addendum, is there any way to extract directly with the header names rather than with column numbers?

Answer 1

I don't know if it's possible to do ranges in awk. You could do a for loop, but you would have to add handling to filter out the columns you don't want. It's probably easier to do this:

awk -F, '{OFS=",";print $1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$20,$21,$22,$23,$24,$25,$30,$33}' infile.csv > outfile.csv 

something else to consider - and this faster and more concise:

cut -d "," -f1-10,20-25,30-33 infile.csv > outfile.csv 

As to the second part of your question, I would probably write a script in perl that knows how to handle header rows, parsing the columns names from stdin or a file and then doing the filtering. It's probably a tool I would want to have for other things. I am not sure about doing in a one liner, although I am sure it can be done.