Greetings -
On 29 Nov 2007, at 09:24, Mark Heitmann wrote:
In my $LD_LIBRARY_PATH /usr/lib is behind /usr/local/lib (for
openldap), although
dovecot-auth was linked with the Solaris lib. The way that works for
me is the
following LDFLAGS directive to the configure command, because the --
with-ldap
flag has no directory option:
LDFLAGS=-L"/usr/local/BerkeleyDB/lib -L/usr/local/lib /usr/local/lib/
libldap-2.4.so.2"
Is there a smarter way to link with the right lib and ignore the
solaris one?
We used to have terrible problems similar to yours when trying to use
LD_LIBRARY_PATH. We now tend to use the "-R" option as well when
compiling to specify unusual/specific library directories...
I think I have the following right:
* "-l libraryname" searches in an ordered list of locations for a
library
named "libraryname".
* "-L dirname" augments the above ordered list of locations with the
directory "dirname".
If the library is a non-shared one then the above should suffice: the
library routines needed by your program are hauled into the resulting
executable and stored there.
However if, as is often the case, the libraries are instead shared
(ie, have a ".so" suffix) then their code is NOT hauled into the
executable, but is instead pulled in when the executable is actually
run. The run-time link-loader does this job.
The run-time link-loader also searches an ordered list of directories,
this time looking for the shared libraries. However this list is NOT
affected by the "-L" option you used when compiling.
Instead the LD_LIBRARY_PATH (and, I think, the LD_RUN_PATH)
environment variable influences this list. However it is easy to end
up with an inappropriate ordering, and so use the wrong shared library
when running your program.
Using the "-R dirname" option at compile time "hardcodes" the named
directory into your executable. When it is run this directory is also
searched for searched libraries, without the need to fiddle on setting
environment variables up.
Typically you would list the same directories for both -L and -R
options when you are using "unusual" places. Eg,
cc -o executable prog.c -lsomelib -L /usr/local/BerkeleyDB/lib -R /
usr/local/BerkeleyDB/lib
(All on one line, of course; the mailer will probably wrap the above.)
It works for us... :-)
Cheers,
Mike B-)
--
The Computing Service, University of York, Heslington, York Yo10 5DD, UK
Tel:+44-1904-433811 FAX:+44-1904-433740
* Unsolicited commercial e-mail is NOT welcome at this e-mail address. *
