You can chain these suckers... so to ensure you do nothing if $x doesn't appear in %my_hash: 

foreach $key ( ($x eq 'key_1') ?  keys %my_hash : exists $my_hash($x) 
+? $x : () ) {
  do a bunch of stuff
}

[download]
noting that if $x does not exist, what you want is an empty list.

In reply to Re^5: Loop once on condition 1, many times on cond. 2? by gone2015
in thread Loop once on condition 1, many times on cond. 2? by punch_card_don

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