4 of 9 portability

C (gcc), 18 17 bytes

f(){puts('@C');}

Note that there's an ETX byte (0x02) between @ and C.

This has been tested with gcc 6.3.1 on Fedora 25, gcc 4.8.4 on Ubuntu 14.04.4, and gcc 4.8.3 on openSUSE 13.2, where it prints the following output.

inux-x86-64.so.2

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