Hans, (Oleg, others correct me if I'm wrong) I think -lpcap tells it to dynamically link to the libpcap.so lib, so the code is not included in the output executable. Then at runtime the system searches the library search path for the .so (set by an env var, can't recall precise name) and loads the code from there. This is called dynamic linking. Linking with an .a file links the code into the output executable and produces a so called statically linked binary. That's what I recall, anyhow - I mostly mess around with Python nowadays :) Sampsa On 10 Apr 2012, at 21:12, H Vlems wrote: Oleg, thank you very much indeed: simh now correctly builds the vax, vax780 and pdp11 executables. Others too, but these matter most for me. Is it possible to explain what the magic does? More precisely: what is the difference between an .a and an .so library? How on earth does -lpcap point to /usr/lib? If the answers are too lengthy or are too complex for an old Algol programmer then say so ;-) Hans -----Oorspronkelijk bericht----- Van: owner-hecnet at Update.UU.SE [mailto:owner-hecnet at Update.UU.SE] Namens Oleg Safiullin Verzonden: maandag, april 2012 8:04 Aan: hecnet at Update.UU.SE Onderwerp: Re: [HECnet] building simh On 04/09/2012 12:33 PM, hvlems at zonnet.nl wrote: Dave, I figured that out too. My system doesn't have a libpcap.a file! If I know how to build one then all would be fine. To build SimH manually wothout libpcap.a (but with libpcap.so.*) you should edit `makefile' and replace line NETWORK_OPT = -DUSE_NETWORK -isystem /usr/local/include /usr/local/lib/libpcap.a with NETWORK_OPT = -DUSE_NETWORK -isystem /usr/local/include -lpcap and then do mkdir BIN make USE_NETWORK=yes