If you try to compare strings using ==, and you have included the use warnings pragma, you will get a warning, as in the example below. However, Perl will still attempt to convert the string into a number. If the string starts with numbers, Perl will use these, otherwise the string equates to 0.
So my conditional,
if ($device_id == '5G0E3663') { ... }compares two zeros and always returns true. Which in my case made bad things happen.
The correct way to compare strings is:
if ($device_id eq '5G0E3663') { ... }h/t perlmeme.