#!/usr/bin/perl

use File::Temp;

use strict;
use warnings;

my @data = qw/a b c d e f g h i j k l m n o p/;
my $file="/tmp/foo.txt";

my (undef, undef, $mode, undef, $uid, $gid) = stat("$file");
$mode = sprintf( "%04o", $mode & 07777);

my $tmp = File::Temp->new( TEMPLATE => 'tempXXXXX',
                           DIR      => '/tmp',
                           SUFFIX   => '.foobar',
                           UNLINK   => 1 );

chmod(oct($mode), $tmp)
    or die("Could not change tempfile to mode $mode.\n");

for my $d (@data) {
    print $tmp $d,"\n";
}

rename($file, "$file.orig")
    or die("Could not rename original file, '$file': $!\n");

rename($tmp, "$file")
    or die("Could not rename temporary file handle: $!\n");

close($tmp);

exit(0);