1<!--$Id: shlib.so,v 10.19 2006/10/05 01:06:05 bostic Exp $--> 2<!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> 3<!--See the file LICENSE for redistribution information.--> 4<html> 5<head> 6<title>Berkeley DB Reference Guide: Dynamic shared libraries</title> 7<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> 8<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> 9</head> 10<body bgcolor=white> 11<a name="2"><!--meow--></a> 12<table width="100%"><tr valign=top> 13<td><b><dl><dt>Berkeley DB Reference Guide:<dd>Building Berkeley DB for UNIX/POSIX systems</dl></b></td> 14<td align=right><a href="../build_unix/install.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../build_unix/test.html"><img src="../../images/next.gif" alt="Next"></a> 15</td></tr></table> 16<p align=center><b>Dynamic shared libraries</b></p> 17<p><b>Warning</b>: the following information is intended to be generic and 18is likely to be correct for most UNIX systems. Unfortunately, dynamic 19shared libraries are not standard between UNIX systems, so there may be 20information here that is not correct for your system. If you have 21problems, consult your compiler and linker manual pages, or your system 22administrator.</p> 23<p>The Berkeley DB dynamic shared libraries are created with the name 24libdb-<b>major</b>.<b>minor</b>.so, where <b>major</b> is 25the major version number and <b>minor</b> is the minor version number. 26Other shared libraries are created if Java and Tcl support are enabled: 27specifically, libdb_java-<b>major</b>.<b>minor</b>.so 28and libdb_tcl-<b>major</b>.<b>minor</b>.so.</p> 29<p>On most UNIX systems, when any shared library is created, the linker 30stamps it with a "SONAME". In the case of Berkeley DB, the SONAME 31is libdb-<b>major</b>.<b>minor</b>.so. It is important to 32realize that applications linked against a shared library remember the 33SONAMEs of the libraries they use and not the underlying names in the 34filesystem.</p> 35<p>When the Berkeley DB shared library is installed, links are 36created in the install lib directory so that 37libdb-<b>major</b>.<b>minor</b>.so, 38libdb-<b>major</b>.so, and libdb.so all refer to the 39same library. This library will have an SONAME of 40libdb-<b>major</b>.<b>minor</b>.so.</p> 41<p>Any previous versions of the Berkeley DB libraries that are 42present in the install directory (such as libdb-2.7.so or 43libdb-2.so) are left unchanged. (Removing or moving old shared 44libraries is one drastic way to identify applications that have been 45linked against those vintage releases.)</p> 46<p>Once you have installed the Berkeley DB libraries, unless they are 47installed in a directory where the linker normally looks for shared 48libraries, you will need to specify the installation directory as part 49of compiling and linking against Berkeley DB. Consult your system 50manuals or system administrator for ways to specify a shared library 51directory when compiling and linking applications with the 52Berkeley DB libraries. Many systems support environment variables 53(for example, LD_LIBRARY_PATH or LD_RUN_PATH), or system configuration 54files (for example, /etc/ld.so.conf) for this purpose.</p> 55<p><b>Warning</b>: some UNIX installations may have an already existing 56<b>/usr/lib/libdb.so</b>, and this library may be an incompatible 57version of Berkeley DB.</p> 58<p>We recommend that applications link against libdb.so (for example, 59using -ldb). Even though the linker uses the file named 60libdb.so, the executable file for the application remembers the 61library's SONAME (libdb-<b>major</b>.<b>minor</b>.so). This 62has the effect of marking the applications with the versions they need 63at link time. Because applications locate their needed SONAMEs when 64they are executed, all previously linked applications will continue to 65run using the library they were linked with, even when a new version of 66Berkeley DB is installed and the file <b>libdb.so</b> 67is replaced with a new version.</p> 68<p>Applications that know they are using features specific to a particular 69Berkeley DB release can be linked to that release. For example, an 70application wanting to link to Berkeley DB major release "3" can link 71using -ldb-3, and applications that know about a particular 72minor release number can specify both major and minor release numbers; 73for example, -ldb-3.5.</p> 74<p>If you want to link with Berkeley DB before performing library 75installation, the "make" command will have created a shared library 76object in the <b>.libs</b> subdirectory of the build directory, such 77as <b>build_unix/.libs/libdb-major.minor.so</b>. If you want 78to link a file against this library, with, for example, a major number 79of "3" and a minor number of "5", you should be able to do something 80like the following:</p> 81<blockquote><pre>cc -L BUILD_DIRECTORY/.libs -o testprog testprog.o -ldb-3.5 82env LD_LIBRARY_PATH="BUILD_DIRECTORY/.libs:$LD_LIBRARY_PATH" ./testprog</pre></blockquote> 83<p>where <b>BUILD_DIRECTORY</b> is the full directory path to the directory 84where you built Berkeley DB.</p> 85<p>The libtool program (which is configured in the build directory) can be 86used to set the shared library path and run a program. For example, 87the following runs the gdb debugger on the db_dump utility after setting 88the appropriate paths:</p> 89<blockquote><pre>libtool gdb db_dump</pre></blockquote> 90<p>Libtool may not know what to do with arbitrary commands (it is hardwired 91to recognize "gdb" and some other commands). If it complains the mode 92argument will usually resolve the problem:</p> 93<blockquote><pre>libtool --mode=execute my_debugger db_dump</pre></blockquote> 94<p>On most systems, using libtool in this way is exactly equivalent to 95setting the LD_LIBRARY_PATH environment variable and then executing the 96program. On other systems, using libtool has the virtue of knowing about 97any other details on systems that don't behave in this typical way.</p> 98<table width="100%"><tr><td><br></td><td align=right><a href="../build_unix/install.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../build_unix/test.html"><img src="../../images/next.gif" alt="Next"></a> 99</td></tr></table> 100<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> 101</body> 102</html> 103
