$append = 0;
if ($append)
{
open(MYOUTFILE, ">clean_text"); #open for write, overwrite }
else
{
open(MYOUTFILE, ">>clean_text"); #open for write, append
}

##</code><code>##

$append = 1;
...
if ( $apped )
{
    # Append to my file
}
else
{
    # Trample all over my irreplaceable data
}

##</code><code>##

my $append = 0;
my $cleanedFile = q{clean_text};
if ( $append )
{
    open my $cleanedFH, q{>>}, $cleanedFile
       or die qq{open: $cleanedFile for append: $!\n};
}
else
{
    open my $cleanedFH, q{>}, $cleanedFile
       or die qq{open: $cleanedFile for overwrite: $!\n};
}