Setting library path in Makefile

bangor has asked for the wisdom of the Perl Monks concerning the following question:

I have made my first XS module and need some help in creating the Makefile.PL. The module uses a library which is installed in '/usr/local/lib'. When I run my script I get an error:

Can't load '/usr/local/lib64/perl5/auto/Mail/SPF_Check.so' for module 
+Mail::SPF_Check: libspf2.so.2: cannot open shared object file: No suc
+h file or directory at /usr/lib64/perl5/DynaLoader.pm line 190.
[download]

If I set the path using

export LD_LIBRARY_PATH='/usr/local/lib'
[download]

The script works. I'm sure there is a way of setting this path in the Makefile (using LIBS => [] ?) but I can't work out the correct syntax.

UPDATE - found the solution, see my comment below.

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Re: Setting library path in Makefile by Fletch (Bishop) on Apr 30, 2019 at 12:58 UTC
The exact syntax is going to depend on your compiler and/or linker, but you're going to want to have it shim in `/usr/local/lib` to the dynamic library search path it bakes into the .so file. What you want in libs is going to be along the lines of `"-R/usr/local/lib -L/usr/local/lib -lspf2"` or something close. If you're using `gcc` in place of `ld` you may need `"-Wl,-R/usr/local/lib"` instead. Alternately you could stick `/usr/local/lib` in your `/etc/ld.so.conf` but be aware that alters the shared library search path for everything on that system. The cake is a lie. The cake is a lie. The cake is a lie.	[reply] [d/l] [select]
Re: Setting library path in Makefile by thanos1983 (Parson) on Apr 30, 2019 at 09:01 UTC
Hello bangor, I am not expert on this area but based on my search I think this is what you are looking for ExtUtils::MakeMaker/PREFIX and LIB attribute. Let me know if this works for you. BR / Thanos Seeking for Perl wisdom...on the process of learning...not there...yet!	[reply] [d/l] [select]
Re: Setting library path in Makefile by bangor (Monk) on May 03, 2019 at 06:42 UTC
After a lot of fruitless searching and experiments I finally found the solution - can't believe how simple it is, and it was right here on this site. `export LDFLAGS=/usr/local/lib perl Makefile.PL` [download] Like LD_LIBRARY_PATH the LDFLAGS is only temporary, but it is only needed while making the lib. Thanks for the help.	[reply] [d/l]
Re: Setting library path in Makefile by Anonymous Monk on May 02, 2019 at 19:41 UTC
Assuming Linux and glibc, you can either add `/usr/local/lib` to `/etc/ld.so.conf` (and run `ldconfig`) to add the directory to the usual runtime search path, or rebuild the library with `-rpath=/usr/local/lib` linker flag (if the linker is `gcc` itself, it should be `-Wl,-rpath=/usr/local/lib` instead). Unfortunately, this stuff is much more platform dependent than Perl itself.	[reply] [d/l] [select]