The Perl Cookbook (Recipe 2.17) has just what you need:

my $number = 987654321;
print commify($number);

sub commify {
    my $text = reverse $_[0];
    $text =~ s/(\d\d\d)(?=\d)(?!\d*\.)/$1,/g;
    return scalar reverse $text
}
[download]

Update: blakem is right. And besides, my answer is incomplete. For a more complete answer, look here.

nice one.

-Blake

In fact, perllocale has an example of doing exactly that!example program that rewrites its command-line parameters as integers correctly formatted in the current locale.

        require 5.004;
        use POSIX qw(locale_h);
        # Get some of locale's numeric formatting parameters
        my ($thousands_sep, $grouping) =
             @{localeconv()}{'thousands_sep', 'grouping'};
        # Apply defaults if values are missing
        $thousands_sep = ',' unless $thousands_sep;
        # grouping and mon_grouping are packed lists
        # of small integers (characters) telling the
        # grouping (thousand_seps and mon_thousand_seps
        # being the group dividers) of numbers and
        # monetary quantities.  The integers' meanings:
        # 255 means no more grouping, 0 means repeat
        # the previous grouping, 1-254 means use that
        # as the current grouping.  Grouping goes from
        # right to left (low to high digits).  In the
        # below we cheat slightly by never using anything
        # else than the first grouping (whatever that is).
        if ($grouping) {
            @grouping = unpack("C*", $grouping);
        } else {
            @grouping = (3);
        }
        # Format command line params for current locale
        for (@ARGV) {
            $_ = int;    # Chop non-integer part
            1 while
            s/(\d)(\d{$grouping[0]}($|$thousands_sep))/$1$thousands_se
+p$2/;
            print "$_";
        }
        print "\n";
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I can help for once! As I found previously!

$number=1234567; # with commas, should be "1,234,567" 
$number =~ s/(\d)(?=(\d{3})+(\D|$))/$1\,/g;
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How can I embed that into an UNIX Korn shell script? By way of an example here is a perl epoch timestamp conversion used in one of my scripts. LASTUPDATE=$(perl -e '($ss, $mm, $hh, $DD, $MM, $YY) = localtime('${LASTUPDATE}'); printf "%02d\/%02d\/%04d\ %02d\:%02d", $MM +1 , $DD , $YY + 1900, $hh, $mm')

How can I embed that into an UNIX Korn shell script?

Can't you sprintf to a variable, comma-munge it, and then print that?

$x = sprintf "%02d\/%02d\/%04d\ %02d\:%02d", $MM +1 , $DD , $YY + 1900
+, $hh, $mm;
$x =~ s/(\d)(?=(\d{3})+(\D|$))/$1\,/g;
print $x;
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You could lose the interim variable on the way to print, but it's easier to follow as above.

-QM
--
Quantum Mechanics: The dreams stuff is made of

I'm not a ksh user, but this script seems to work for me.

===

cat ~/.local/bin/commafy

#!/usr/bin/perl -nl
$_ =~ s/(\d)(?=(\d{3})+(\D|$))/$1\,/g;
print;
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===

My usage (to find out that a recent nix build used 18 GB of space):

$ find /nix/store -cmin -150 | perl -nle '$sum+=-s "$_";END{print $sum
+}' | commafy
18,025,136,505
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2018-12-16 Athanasius added code and paragraph tags

Uh, this doesn't work.

Looks fine to me....

#!/usr/bin/perl -wT
use strict;

my $number='1234567890.01'; # with commas, should be "1,234,567,890.01
+" 
print "N=$number\n";

$number =~ s/(\d)(?=(\d{3})+(\D|$))/$1\,/g;
print "N=$number\n";
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Output

N=1234567890.01
N=1,234,567,890.01
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Care to elaborate on which part doesn't work?

-Blake

use Number::Format;
my $uuooop = new Number::Format;
print $uuooop->format_number("1234567890.0123456789",2);
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