csvcut

#!/usr/bin/env python
"""
Like cut, but for CSVs. To be used from a shell command line.

Note that fields are zero-based, as opposed to 'cut' where they are 1-based.

Should use something better than getopt, but this works...

Usage: 
    csvcut foobar.csv
    (prints the first column of each row of foobar.csv)
    
    head -10 foobar.csv | csvcut -f 0,2
    (prints the first and third columns of the first ten lines of foobar.csv)

    csvcut -f 0,2 -d "|" foobar.csv
    (prints the first and third columns of the pipe-delimited foobar.csv)

    csvcut -f 0,2 -t foobar.csv
    (prints the first and third columns of the tab-delimited foobar.csv
     if present, the -d option will be ignored.)

    csvcut -h foobar.csv
    (prints the values of the first line of foobar.csv, preceded by the field index which would 
     be used to display that column.  If present, the -f option will be ignored.)

    csvcut -f 0,1,2 -d "|" -o , foobar.csv
    (prints the first three columns of the pipe-delimited foobar.csv; output
    will be comma-delimited.)

    csvcut -f 0,1,2 -o "|" foobar.csv
    (prints the first three columns of the comma-delimited foobar.csv; output
    will be pipe-delimited.)

    csvcut -f : -o "|" foobar.csv
    (prints all the columns of the comma-delimited foobar.csv; output will be
    pipe-delimited.)

    csvcut -f 0,1 -d "," -q "|" foobar.csv
    (prints the first two columns of the comma-delimited, pipe-quoted foorbar.csv.)
"""
import sys, csv, getopt
opts, args = getopt.getopt(sys.argv[1:], "f:d:o:q:ht", [])
if args:
    i = open(args[0],"U")
else:
    i = sys.stdin

delimiter = ','
output_delimiter = ' '
cols = [0, ]
show_headers = False

if opts:
    opts = dict(opts)
    show_headers = '-h' in opts
    if '-f' in opts:
        cols = opts['-f'].split(",")
    if '-t' in opts:
        delimiter = "\t"    
    elif '-d' in opts:
        delimiter = opts['-d']
    if '-o' in opts:
        output_delimiter = opts['-o']
    if '-q' in opts:
        quotechar = opts['-q']
    else:
        quotechar = None

for row in csv.reader(i, delimiter=delimiter, quotechar=quotechar):
    if show_headers:
        for i,c in enumerate(row):
            print "%3i: %s" % (i,c)
        break
    writer = csv.writer(sys.stdout, delimiter=output_delimiter)
    if cols == [':']:
        cols = range(len(row))
    writer.writerow([row[int(c)] for c in cols])

Added "U" to the open call to handle common case of Mac OS Excel CSV exports, which have Mac line feeds instead of UNIX.

If you're using this, there's a newer version merged into csvkit -- https://github.com/wireservice/csvkit :)