Others have offered varied solutions. Alternatively, you can use splice. Once you have read all the names into an array, you can loop through that array to gather items 3 at a time:

while(@names) {
    my ($i, $j, $k)  = splice (@names, 0, 3);
    printf('$i is %s, $j is %s, $k is %s', $i, $j, $k);
    print "\n";
}
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Note that if you have strict or warnings enabled, you will get errors like: "Use of uninitialized value $k in printf". You can add error/null checking here to handle all of these. This would also mutate the @names array - keep a defensive copy around. :-)