If you don't want to risk races, use sysopen and loop until you can create the file yourself:

#!/usr/bin/perl -w
use strict; use warnings; use 5.010;

use Fcntl qw/ O_CREAT O_EXCL O_WRONLY /;

my $fh = open_next( "Results", ".txt" );
print $fh "Hello!\n";


sub open_next {
    my ($prefix, $suffix) = @_;
    my $number = 0;
    my $FH;
    until (sysopen($FH, ($prefix . ($number || "") .$suffix), O_WRONLY
+|O_EXCL|O_CREAT)) {
        $number++;
    }
    return $FH;
}

[download]

Good Day,
    Dean

In reply to Re: Sequentially numbering output files rather than overwriting an existing file by duelafn
in thread Sequentially numbering output files rather than overwriting an existing file by TJCooper

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