Is there any way to check if an array has been initialized? I am executing a command and that output is going into an array. If the command has no output then the array does not get initialized. Is there a way to check that?

Your assumptions are wrong:

after

my @array1;
my @array2 = some_code();
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is run, @array1 and @array2 will both be initialized. @array1 will be empty: you can check for that using:

if (@array1) {
  print "not empty\n";
}
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@array2 will contain whatever some_code() returns. some_code() will allways return a list, because it's called in list context (caused by the assignment to @array2).

If some_code returns like this:

  return (); # an empty list
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@array2 will be empty, like @array1 above.

If some_code returns like this:

  return undef; # undefined scalar
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@array2 will contain 1 element which will be undefined.

If some_code returns like this:

  return;  # "return false"
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@array2 will be empty (return; without arguments returns an empty list in list context, and undef in scalar context)

If some_code does not use a return statement, the last statement in some_code will be executed in list context and its value will be returned.