SuSE

pkg-config --cflags also gives you the include paths and such to compile. Hopefully that'll force it to use the right definitions for the one of the three --libs picks.

Well it does seem to link properly using -lusb-1.0 and I have it working now. There appear to have been some changes in the way this hardware works and I may not actually have to link to the usb lib anymore, go figure.

Thanks again for the help, I'm sure that learning about pkg-config will continue to prove useful.

LMHmedchem

Try ldd ./myprogram to see what libraries it loads, I suspect it does actually load one of your libusb so files.

This is the list of libs that are loaded,
linux-vdso.so.1 (0x00007fffd1595000)
libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f85ac109000)
libusb-1.0.so.0 => /usr/lib64/libusb-1.0.so.0 (0x00007f85abef9000)
libstdc++.so.5 => /usr/lib64/libstdc++.so.5 (0x00007f85abc17000)
libm.so.6 => /lib64/libm.so.6 (0x00007f85ab919000)
libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007f85ab703000)
libc.so.6 => /lib64/libc.so.6 (0x00007f85ab355000)
/lib64/ld-linux-x86-64.so.2 (0x00007f85ac325000)
librt.so.1 => /lib64/librt.so.1 (0x00007f85ab14d000)

I'm not sure this tells me if my app is using anything in the library or not because I linked to the usb library in make. If I have -lusb-1.0 in my link rule, will libusb-1.0 appear on this list even if there is never anything in the library that gets called?

I guess I probably need to build it without the link and see if it still works.

LMHmedchem

If you leave out -lusb-1.0 and it still links, then you are correct.