No need to nest loops. The condition you mentioned can be checked without iterating through each entire hash. You still have to iterate through the array, though.

for (@$pages) {
  $_->{flag} = 1 if $_->{url} eq "/html/about.html";
}
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If you want to get really fancy, it can be a one liner, but I think that using logical connectives (and/or) for flow control hurts readability, especially in a complex statement with modifiers.

$_->{url} eq "/html/about.html" and $_->{flag} = 1 for @$pages;
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