Hi. Seems the above replies have already solved your problem. But just a point of (hopefully) correction here. Do you have to keep explicitly using $_ ? Your code would be much more readable, you know, if you didn't do that. And use \s for your space, instead of a space character.

use strict;
my $file = '.';
opendir(MYDIR,$file);
my @files = readdir(MYDIR);

foreach (@files)
{
next if( m/^\.+$/); 
    if ( m/\s/g ) 
    {
        my $oldfile = $_;
        s/\s/_/g;
                    if (! -e)
                    {
                         rename $oldfile, $_;
                    }
                    else
                    {
                        print "Could not rename $oldfile because ${_} 
+name already exists and can not be overwritten\n";
                    }
             
    }
print "$_\n";
}
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