Sorting a tab delimited file

Question

Using bash, this will do the trick:

$ sort -t$'\t' -k3 -nr file.txt

Notice the dollar sign in front of the single-quoted string. You can read about it in the ANSI-C Quoting sections of the bash man page.

By default the field delimiter is non-blank to blank transition so tab should work just fine.

However, the columns are indexed base 1 and base 0 so you probably want

sort -k4nr file.txt

to sort file.txt by column 4 numerically in reverse order. (Though the data in the question has even 5 fields so the last field would be index 5.)

You need to put an actual tab character after the -t\ and to do that in a shell you hit ctrl-v and then the tab character. Most shells I've used support this mode of literal tab entry.

Beware, though, because copying and pasting from another place generally does not preserve tabs.

The $ solution didn't work for me. However, By actually putting the tab character itself in the command did: sort -t'' -k2

pipe it through something like awk '{ print print $1"\t"$2"\t"$3"\t"$4"\t"$5 }'. This will change the spaces to tabs.

In general keeping data like this is not a great thing to do if you can avoid it, because people are always confusing tabs and spaces.

Solving your problem is very straightforward in a scripting language like Perl, Python or Ruby. Here's some example code:

#!/usr/bin/perl -w

use strict;

my $sort_field = 2;
my $split_regex = qr{\s+};

my @data;
push @data, "7 8\t 9";
push @data, "4 5\t 6";
push @data, "1 2\t 3";

my @sorted_data = 
    map  { $_->[1] }
    sort { $a->[0] <=> $b->[0] }
    map  { [ ( split $split_regex, $_ )[$sort_field], $_ ] }
    @data;

print "unsorted\n";
print join "\n", @data, "\n";
print "sorted by $sort_field, lines split by $split_regex\n";
print join "\n", @sorted_data, "\n";