Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Tue, 17 Jul 2007 10:48:51 -0500

Hi Mark,

> The line 
> 
> asyn_LIBS += gpib
> 
> tells the EPICS build system to look for libgpib.a in the EPICS 
> directories.  This does not seem to be correct, that is a system 
> library, not an EPICS library.  So I think that line should be

No, setting asyn_LIBS like that tells the build system to link the asyn binary with libgpib (it results in the link line having -lgpib added to it). If libgpib is not being found you can explicitly tell the build system where it is by setting the gpib_DIR variable in the Makefile.  Alternatively and more generally you can tell the linker to look in /usr/local/lib automatically by listing that directory in /etc/ld.so.conf or by creating a file in /etc/ld.so.com.d with the appropriate setting.

> Note, I think that LD_LIBRARY_PATH is used only at run-time to find 
> .so files, not when building applications, so I would not expect it 
> to work.  

Sorry, but you're wrong there too; having LD_LIBRARY_PATH set at build-time is actually frowned upon nowadays because if it's set at link time its value will be saved in the binary and the path re-used at runtime, which is contrary to how most Linux package management systems like to work (they build in a different location to their final runtime location, so their link-time paths will not be valid at runtime).

> I don't think you have explained how libgpib.a got in the asyn 
> tree, if it really is there.

I agree, I think that file should be deleted.

- Andrew

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System