在链接libmysqlclient的时候，发现出现如下错误：
/usr/lib64/mysql/libz.a(adler32.o)(.text+0x0): In function `adler32':
/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/adler32.c:66: multiple definition of `adler32'
/usr/lib64/mysql/libmysqlclient.a(adler32.o)(.text+0x0):/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/adler32.c:66: first defined here
/usr/lib64/mysql/libz.a(adler32.o)(.text+0x340): In function `adler32_combine':
/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/adler32.c:138: multiple definition of `adler32_combine'
/usr/lib64/mysql/libmysqlclient.a(adler32.o)(.text+0x340):/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/adler32.c:138: first defined here
/usr/lib64/mysql/libz.a(compress.o)(.text+0x0): In function `compress2':
/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/compress.c:28: multiple definition of `compress2'
/usr/lib64/mysql/libmysqlclient.a(compress.o)(.text+0x0):/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/compress.c:28: first defined here
/usr/lib64/mysql/libz.a(compress.o)(.text+0xf0): In function `compress':
/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/compress.c:68: multiple definition of `compress'
/usr/lib64/mysql/libmysqlclient.a(compress.o)(.text+0xf0):/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/compress.c:68: first defined here
...
/usr/lib64/mysql/libz.a(inftrees.o)(.text+0x0): In function `inflate_table':
/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/inftrees.c:39: multiple definition of `inflate_table'
/usr/lib64/mysql/libmysqlclient_r.a(inftrees.o)(.text+0x0):/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/inftrees.c:39: first defined here
/usr/lib64/mysql/libz.a(trees.o)(.rodata+0x0): In function `init_block':
/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/trees.c:417: multiple definition of `_length_code'
/usr/lib64/mysql/libmysqlclient_r.a(trees.o)(.rodata+0x0):/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/trees.c:417: first defined here
/usr/lib64/mysql/libz.a(trees.o)(.rodata+0x100): In function `pqdownheap':
/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/trees.c:459: multiple definition of `_dist_code'
/usr/lib64/mysql/libmysqlclient_r.a(trees.o)(.rodata+0x100):/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/trees.c:459: first defined here
/usr/lib64/mysql/libz.a(trees.o)(.text+0x80): In function `_tr_init':
/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/trees.c:387: multiple definition of `_tr_init'
/usr/lib64/mysql/libmysqlclient_r.a(trees.o)(.text+0x80):/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/trees.c:387: first defined here
/usr/lib64/mysql/libz.a(trees.o)(.text+0xd20): In function `_tr_align':
/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/trees.c:894: multiple definition of `_tr_align'
/usr/lib64/mysql/libmysqlclient_r.a(trees.o)(.text+0xd20):/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/trees.c:894: first defined here
/usr/lib64/mysql/libz.a(trees.o)(.text+0x14b0): In function `_tr_stored_block':
/export/home/my/tmp-200903301116-5.1.34-19266/rpm/BUILD/mysql-5.1.34/zlib/trees.c:872: multiple definition of `_tr_stored_block'
从这些信息上看 libmysqlclient_r.a中的一些.o已经在libz.a中定义过了，所以出现了重定义。那么我们只要把其中一个.a文件中重定义过的.o剔除掉就可以了，方法就是：
cp -p /usr/lib64/mysql/libmysqlclient_r.a /usr/lib64/mysql/libmysqlclient_r.a.orig
ar d /usr/lib64/mysql/libmysqlclient_r.a adler32.o compress.o crc32.o deflate.o gzio.o infback.o inffast.o inflate.o inftrees.o trees.o uncompr.o zutil.o
这代表了一类问题，就是当出现 multiple definition of XXX 的时候都可以采用类似的方法来解决。
另外这里有两个特别要注意的地方：
1，lib64，如果安装的是32位版本，静态库可能就会是在/usr/lib64/mysql中。
2，_r，这个是线程安全版本的库的命名方式， 比如目录/usr/lib64/mysql中就有两个libmysqlclient，一个是libmysqlclient.a，还有一个是libmysqlclient_r.a。这个要特别注意，到底是用哪个静态库
转载自 http://www.cnblogs.com/welkinwalker/archive/2011/02/24/1963814.html