LibEvent的使用过程记录

    The libevent API provides a mechanism to execute a callback function when a specific event occurs on a file descriptor or after a timeout has been reached. Furthermore, libevent also support callbacks due to signals or regular timeouts.(来自官网表述)

1从http://libevent.org/下载最新的源码libevent-2.0.22-stable.tar.gz编译；

tar -zxvf ./libevent-2.0.22-stable.tar.gz

mv libevent-2.0.22-stable ./libevent

./configure --prefix=*****

make

make install

2.编写demo测试 略

g++ ./libevent.cpp -g -O0 -levent -L /usr/local/lib

./a.out: error while loading shared libraries: libevent-2.0.so.5: cannot open shared object file: No such file or directory

ldd ./a.out 
        linux-vdso.so.1 =>  (0x00007fff95116000)
        libevent-2.0.so.5 => not found
        libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x000000363b000000)
        libm.so.6 => /lib64/libm.so.6 (0x0000003638800000)
        libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x000000363ac00000)
        libc.so.6 => /lib64/libc.so.6 (0x0000003638c00000)
        /lib64/ld-linux-x86-64.so.2 (0x0000003638400000)

 libevent-2.0.so.5 没有找到

查看位置

 whereis libevent-2.0.so.5
libevent-2.0.so: /usr/local/lib/libevent-2.0.so.5

[root@chenfeng test]# g++ ./libevent.cpp -o libevent -g -O0 -levent -L/usr/local/lib -Wl,rpath=/usr/local/lib 
/usr/bin/ld: rpath=/usr/local/lib: No such file: No such file or directory

collect2: ld 返回 1

来自http://gcc.gnu.org/ml/gcc-help/2005-12/msg00017.html

The -L option supplies a colon-separated library path that is to besearched at LINK TIME for libraries. Thuscc -o foo foo.c -L/usr/local/lib -lfoomeans that either libfoo.a or libfoo.so should be found in either/usr/local/lib, or elsewhere in the default search patch (inGNU/Linux, the directories can be listed in /etc/ld.so.conf, and thecache updated by running /etc/ldconfig).

Whether the .a or .so form of the library is needed is platformdependent (e.g., IBM AIX uses only the .a form), and also dependent oncompiler options to select dynamic or static linking.  The default isnormally dynamic linking to save disk space and waste CPU time.However, this means while that the executable foo may have beensuccessfully linked against a shared library, at RUN TIME, therun-time loader looks for it in the default search path, possiblyprefixed by a colon-separated list of libraries supplied by theLD_LIBRARY_PATH variable.If, in our example, /usr/local/lib is not part of the default path,then the run-time loader will not be able to find the shared library,EVEN THOUGH LINKING SUCCEEDED (because of the -L/usr/local/liboption).

otice the "(file not found") line.  That library is actually presenton that system in /usr/local/lib, and I can make it succeed like this:% env -i LD_LIBRARY_PATH=/usr/local/lib ldd /usr/local/bin/emacs        libXaw3d.so.5 =>         /usr/local/lib/libXaw3d.so.5        libXmu.so.4 =>   /usr/lib/libXmu.so.4...Thus, when shared libraries are present in nondefault directories, youneed to supply an additional linker option, usually -R or -Wl,-rpath=,with a run-time library path.  Our example above becomes for gccgcc -o foo foo.c -L/usr/local/lib -lfoo -Wl,-rpath=/usr/local/lib

In a Makefile, I would write this asgcc -o foo foo.c -L$(prefix)/lib -lfoo -Wl,-rpath=$(prefix)/lib

[root@chenfeng test]# g++ ./libevent.cpp  -o livevent -g -O0  -L/usr/local/lib -levent -Wl,-rpath=/usr/local/lib[root@chenfeng test]# ./livevent

编译通过

OK