not seems Perl related: a hint from my experience: when you doubt about a Perl bug you wrong or became a master..
Anyway /y is not a recognized switch, see regedit, the correct sysntax seems to be: 
REGEDIT /E pathname

regedit /E  y:\reg_cmd2.reg "/"

[download]
I tryed and the first time i had the registry dumped, then i deleted the file and i was no more able to dump a second time... seems a very bad feature coming from the ancient past: now only usable to launch the GUI

Try instead reg as in reg  EXPORT HKU c:\file.reg
HtH
L*
There are no rules, there are no thumbs..
Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.

In reply to Re: registry dump to file output differs from DOS cli and system ? by Discipulus
in thread registry dump to file output differs from DOS cli and system ? by gepebril69

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