Sys::Hostname tries to fall back to system utilities like 'hostname' and 'uname -n' to get the host name, so the problem probably has something to do with your $ENV{PATH}.

i was able to get your code to work by adding the following line:

local %ENV = (PATH => '/bin');
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this should work under UNIX as long as 'uname' or 'hostname' is in '/bin'.

a better way to make it work is to create "syscall.ph" for the systems you'll be using by running 'h2ph /usr/include/syscall.h'. however, upon testing, even this didn't fully avoid tainting problems on my system (GNU/Linux).