note LanX <i>> <c>my @uniq = keys %{ {%hash1, %hash2} };</c></i><P> From inside out:<P> - First the two hashes are flattened to lists, which are combined to a long list.<P> - Building a new (anonymous) hashref will eliminate duplicated entries from that hash ¹<P> - To be able to extract² the [doc://keys] you still need to dereference this ano-hashref with <c>%{..}</c>. <P> step by step:<P> <c> DB<111> %hash1= (a=>1,b=>2) => ("a", 1, "b", 2) DB<112> %hash2= (a=>1,c=>3) => ("a", 1, "c", 3) DB<113> (%hash1, %hash2) => ("a", 1, "b", 2, "c", 3, "a", 1) DB<115> + {%hash1, %hash2} => { a => 1, b => 2, c => 3 } DB<117> %{ {%hash1, %hash2} } => ("c", 3, "a", 1, "b", 2) DB<118> keys %{ {%hash1, %hash2} } => ("c", "a", "b") </c><P> <!-- Node text goes above. Div tags should contain sig only --> <div class="pmsig"><div class="pmsig-708738"> <p>Cheers Rolf </div></div><P> UPDATES:<P> ¹) because repeated keys will be overwritten.<P> ²) at least with older perl-versions, see [Athanasius]' [id://1011266|remark] 1011256 1011256