while(<INFILE>){
   chomp;
   ($index,@record)=split/[:,]/;
   push @{$records{$index}},@record;
}

##</code><code>##

for $index (sort{$a<=>$b}(keys (%records))){
        print $OUTFILE "$index: ",join(",",(sort{$a<=>$b}(@{$records{$index}}))),"\n";
}

##</code><code>##

#!/usr/bin/perl
use strict;
use warnings;
my @files=qw(temp.data temp1.data temp2.data);
my ($file,$index, %records,$INFILE,$OUTFILE);
for $file (@files){
        open($INFILE,"<","$file")|| die "Failed to open $file: $!";
        while(<$INFILE>){
                my @record;
                chomp;
                ($index,@record)=split/[:,]/;
                push @{$records{$index}},@record;
        }
        close $INFILE;
}

open ($OUTFILE,">","newfile.data")|| die "Failed to open newfile.data: $!";
for $index (sort{$a<=>$b}(keys (%records))){
        print $OUTFILE "$index: ",join(",",(sort{$a<=>$b}(@{$records{$index}}))),"\n";
}
close $OUTFILE