NOTES FOR UNIX LIKE PLATFORMS | |
============================= | |
For Unix/POSIX runtime systems on Windows, please see NOTES.WIN. | |
Shared libraries and installation in non-standard locations | |
----------------------------------------------------------- | |
Binaries on Unix variants expect to find shared libraries in standard | |
locations, such as /usr/lib, /usr/local/lib and some other locations | |
configured in the system (for example /etc/ld.so.conf on some systems). | |
If the libraries are installed in non-standard locations, binaries | |
will not find them and therefore fail to run unless they get a bit of | |
help from a defined RPATH or RUNPATH. This can be applied by adding | |
the appropriate linker flags to the configuration command, such as | |
this (/usr/local/ssl was the default location for OpenSSL installation | |
in versions before 1.1.0): | |
$ ./config --prefix=/usr/local/ssl --openssldir=/usr/local/ssl \ | |
-Wl,-rpath,/usr/local/ssl/lib | |
Because the actual library location may vary further (for example on | |
multilib installations), there is a convenience variable in Makefile | |
that holds the exact installation directory and that can be used like | |
this: | |
$ ./config --prefix=/usr/local/ssl --openssldir=/usr/local/ssl \ | |
-Wl,-rpath,'$(LIBRPATH)' | |
On modern systems using GNU ld.so, a better choice may be to use the | |
new dtags, like this: | |
$ ./config --prefix=/usr/local/ssl --openssldir=/usr/local/ssl \ | |
-Wl,--enable-new-dtags,-rpath,'$(LIBRPATH)' | |
This sets DT_RUNPATH instead of DT_RPATH. DT_RUNPATH is considered after | |
the environment variable LD_LIBRARY_PATH, while DT_RPATH is considered | |
before that environment variable (which means that the values in that | |
environment variable won't matter if the library is found in the | |
paths given by DT_RPATH). |