pcut

#!/usr/bin/perl -w

use strict;

my @cols;
if (scalar(@ARGV) >= 1 && $ARGV[0] =~ /^-f((?:\d+,)*\d+)$/) {
  @cols = split(/,/, $1);
  shift @ARGV;
} elsif (scalar(@ARGV) >= 2 && $ARGV[0] =~ /^-f$/ && $ARGV[1] =~ /^((?:\d+,)*\d+)$/) {
  @cols = split(/,/, $1);
  shift @ARGV;
  shift @ARGV;
} else {
  print "Usage: $0 -f <num>\n";
  exit(1);
}

my $max_col = -1;
foreach my $col (@cols) {
  $max_col = $col if $max_col < $col;
  $col--;
}

my $error = 0;
while (<>) {
  my $line = $_;

  $line =~ s/^\s*//;
  $line =~ s/\s*$//;
  
  my @values = split(/\s+/, $line);
  if (scalar(@values) < $max_col) {
    $error = 1;
  } else {
    print join("\t",@values[@cols]) . "\n";
  }
}

if ($error) {
  print STDERR "Error, some lines omitted because they didn't have column $max_col\n";
}