Interesting sample. I've tried the following so far, but will have to redo my location for the temporary file based on the location of the destination. That is so it will be on the same partition as the file it is replacing. Otherwise, I get the error, "Could not rename temporary file handle: Invalid cross-device link".

#!/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);
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