Keep only certain columns in a csv file

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# 1  
Old 08-05-2011
Keep only certain columns in a csv file

I have a file that has 500+ columns but only need 15 of those and all the other ones can be removed.

What is the best way to do this? Can I get some examples please?
# 2  
Old 08-05-2011
With awk you can do something like:
awk -F, '{print $1,$2,$4,$18,$20}'

the numbers being the column # of course.
# 3  
Old 08-05-2011

The solution of 'neutronscott' must work and it's easy to program. I did one in 'perl' and althought perhaps you don't need it, could be useful for another one.
$ cat
use warnings;
use strict;

@ARGV >= 3 or die <<USAGE;
Usage: perl $0 file_separator #column #column #column ... file
Example: perl $0 "," 7 12 41 myfile.csv

## Get arguments:
## First one ($file_separator) -> Separator of csv file.
## Last one ($file) -> The file to process.
## Rest of arguments (@columns) -> The numbers of the columns to print.
my $file_separator = shift;
my $file = pop @ARGV;
my @columns = grep { /^\d+$/ } @ARGV;

open my $fh, "<", $file or die "Cannot open file $file: $!\n";

## Index of columns begin in 0.
@columns = map { --$_ } @columns;

while ( <$fh> ) {

        ## Omit blank lines.
        next unless /\S/;

        ## Remove end of line character.

        ## Once in the processing of the file, count number of fields and remove
        ## from the array of columns those number bigger or incorrect (not
        ## positives).
        if ( 1 .. 1 ) {
                my $line_fields = eval "tr/$file_separator/$file_separator/";
                @columns = grep { $_ < $line_fields && $_ >= 0  } @columns; 

        ## Split columns and join only those pointed out in parameters.
        my @line_columns = split /$file_separator/;
        my $outline = join "$file_separator", @line_columns[ @columns ];
        printf "%s\n", $outline;

close $fh or warn "Cannot close file $file: $!\n";
$ perl
Usage: perl file_separator #column #column #column ... file
Example: perl "," 7 12 41 myfile.csv
$ perl "," 1 4 7 36 infile
... ((Output)) ...

# 4  
Old 08-05-2011
I used the one neutronscott put out. But I would be interested in what you have done birei. I will try that way just to see if I can get it to work for me.

Thanks to both!
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