use strict;
use warnings;
my @ids       = qw(a b c d e f g h);
my $chosen_id = '';

my $last_id = '';
if (open (my $fh, 'recent')) {
  $last_id = <$fh>;
  close ($fh);
}

while (1) {
    $chosen_id = @ids[ int( rand(@ids) ) ];
    print "chosen:  $chosen_id\n";
    last if $chosen_id ne $last_id;
    print "problem: $chosen_id is on the recent list, choose again\n";
}

# replace the file
open (my $fh, '>', 'recent') 
  or die "failed to open recent for write: $!\n";
print $fh $chosen_id;
close ($fh);