Sorting a tab delimited file

Question

I have a data with the following format:

foo<tab>1.00<space>1.33<space>2.00<tab>3

Now I tried to sort the file based on the last field decreasingly. I tried the following commands but it wasn't sorted as we expected.

$ sort -k3nr file.txt  # apparently this sort by space as delimiter

$ sort -t"\t" -k3nr file.txt
  sort: multi-character tab `\\t'

$ sort -t "`/bin/echo '\t'`" -k3,3nr file.txt
  sort: multi-character tab `\\t'

What's the right way to do it?

Here is the sample data.

Answer 1

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.

Answer 2

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.)

Answer 3

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.

Answer 4

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

Answer 5

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

Answer 6

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";

Answer 7

I wanted a solution for Gnu sort on Windows, but none of the above solutions worked for me on the command line.

Using Lloyd's clue, the following batch file (.bat) worked for me.

Type the tab character within the double quotes.

C:\>cat foo.bat

sort -k3 -t"    " tabfile.txt

Answer 8

I was having this problem with sort in cygwin in a bash shell when using 'general-numeric-sort'. If I specified -t$'\t' -kFg, where F is the field number, it didn't work, but when I specified both -t$'\t' and -kF,Fg (e.g -k7,7g for the 7th field) it did work. -kF,Fg without the -t$'\t' did not work.

Answer 9

If you want to make it easier for yourself by only having tabs, replace the spaces with tabs:

tr " " "\t" < <file> | sort <options>