mysql - ld 找不到 libmysqlclient

Question

我记得，几年前当我开始使用 mySQL 时，为了找到库(尤其是 mySQL 库!)而“就这样”设置东西是一场噩梦。就我而言，我相信 ldconfig 是解决问题的工具。快进到 2012 年 - 刚刚安装了一个新的“主要”系统，其中包括 64 位 Ubuntu 12.04，我正在确保我的所有源代码都能编译。想象一下我对 libmysqlclient 回到同一条船上感到惊讶。

我的网络搜索揭示了很多可以尝试的东西，但没有任何帮助。一路上，我发现了这个技巧:gcc ... mysql_config --cflags --libs - 非常好，但没有帮助。

因此，例如，结果:

gcc -D_FILE_OFFSET_BITS=64 `mysql_config --cflags --libs` \
            -o check-my-ip \
            -s check-my-ip.c ../common/ini-file.c

是

 /tmp/ccxAgCqr.o: In function `updateTables':
 /usr/local/src/check-my-ip/check-my-ip.c:373: undefined reference to `mysql_init'
 /usr/local/src/check-my-ip/check-my-ip.c:374: undefined reference to `mysql_real_connect'
 /usr/local/src/check-my-ip/check-my-ip.c:381: undefined reference to `mysql_error'
 /usr/local/src/check-my-ip/check-my-ip.c:381: undefined reference to `mysql_errno'
 /usr/local/src/check-my-ip/check-my-ip.c:397: undefined reference to `mysql_field_count'
 /usr/local/src/check-my-ip/check-my-ip.c:398: undefined reference to `mysql_use_result'
 /usr/local/src/check-my-ip/check-my-ip.c:399: undefined reference to `mysql_fetch_row'
 /usr/local/src/check-my-ip/check-my-ip.c:419: undefined reference to `mysql_free_result'
 /usr/local/src/check-my-ip/check-my-ip.c:422: undefined reference to `mysql_field_count'
 /usr/local/src/check-my-ip/check-my-ip.c:429: undefined reference to `mysql_close'
 /tmp/ccxAgCqr.o: In function `myQuery':
 /usr/local/src/check-my-ip/check-my-ip.c:439: undefined reference to `mysql_query'
 /usr/local/src/check-my-ip/check-my-ip.c:441: undefined reference to `mysql_error'
 /tmp/ccxAgCqr.o: In function `indexExists':
 /usr/local/src/check-my-ip/check-my-ip.c:464: undefined reference to `mysql_field_count'
 /usr/local/src/check-my-ip/check-my-ip.c:465: undefined reference to `mysql_use_result'
 /usr/local/src/check-my-ip/check-my-ip.c:466: undefined reference to `mysql_fetch_row'
 /usr/local/src/check-my-ip/check-my-ip.c:471: undefined reference to `mysql_free_result'
 collect2: ld returned 1 exit status
 make: *** [check-my-ip] Error 1

mysql_config --cflags --libs 的输出是:

-I/usr/include/mysql -DBIG_JOINS=1  -fno-strict-aliasing  -g
-L/usr/lib/x86_64-linux-gnu -lmysqlclient -lpthread -lz -lm -lrt -ldl

这些是一些可能有助于诊断的其他命令:

$ ldconfig -p | grep mysql

    libmysqlclient.so.18 (libc6,x86-64) => /usr/lib/x86_64-linux-gnu/libmysqlclient.so.18
    libmysqlclient.so (libc6,x86-64) => /usr/lib/x86_64-linux-gnu/libmysqlclient.so

 $ ls -l /usr/lib/x86_64-linux-gnu/libmysqlclient.so.18
 lrwxrwxrwx 1 root root 24 Jun 11 10:21 /usr/lib/x86_64-linux-gnu/libmysqlclient.so.18 -> libmysqlclient.so.18.0.0
 $ ls -l /usr/lib/x86_64-linux-gnu/libmysqlclient.so.18.0.0
 -rw-r--r-- 1 root root 3408136 Jun 11 10:21 /usr/lib/x86_64-linux-gnu/libmysqlclient.so.18.0.0

我做了一个 aptitude search libmysql 并注意到有 37 行，其中大部分具有 i386 名称(例如:libmysqld-pic:i386)，我注意到该输出中有 x86_64(或 -64)零行；那是问题的一部分吗？ (这里是那 37 行)

 $ aptitude search libmysql
 p   libmysql++-dev                            - MySQL C++ library bindings (development)
 p   libmysql++-dev:i386                       - MySQL C++ library bindings (development)
 p   libmysql++-doc                            - MySQL C++ library bindings (documentation and exampl
 p   libmysql++3                               - MySQL C++ library bindings (runtime)
 p   libmysql++3:i386                          - MySQL C++ library bindings (runtime)
 p   libmysql-cil-dev                          - MySQL database connector for CLI
 p   libmysql-diff-perl                        - module for comparing the table structure of two MySQ
 p   libmysql-java                             - Java database (JDBC) driver for MySQL
 p   libmysql-ocaml                            - OCaml bindings for MySql
 p   libmysql-ocaml:i386                       - OCaml bindings for MySql
 p   libmysql-ocaml-dev                        - OCaml bindings for MySql
 p   libmysql-ocaml-dev:i386                   - OCaml bindings for MySql
 v   libmysql-ocaml-dev-dnim6:i386             -
 v   libmysql-ocaml-dev-jygp6                  -
 v   libmysql-ocaml-dnim6:i386                 -
 v   libmysql-ocaml-jygp6                      -
 p   libmysql-ruby                             - Transitional package for ruby-mysql
 v   libmysql-ruby:i386                        -
 p   libmysql-ruby1.8                          - Transitional package for ruby-mysql
 v   libmysql-ruby1.8:i386                     -
 p   libmysql-ruby1.9.1                        - Transitional package for ruby-mysql
 v   libmysql-ruby1.9.1:i386                   -
 p   libmysql6.4-cil                           - MySQL database connector for CLI
 i   libmysqlclient-dev                        - MySQL database development files
 p   libmysqlclient-dev:i386                   - MySQL database development files
 v   libmysqlclient15-dev                      -
 v   libmysqlclient15-dev:i386                 -
 i A libmysqlclient18                          - MySQL database client library
 p   libmysqlclient18:i386                     - MySQL database client library
 p   libmysqlcppconn-dev                       - MySQL Connector for C++ (development files)
 p   libmysqlcppconn-dev:i386                  - MySQL Connector for C++ (development files)
 p   libmysqlcppconn5                          - MySQL Connector for C++ (library)
 p   libmysqlcppconn5:i386                     - MySQL Connector for C++ (library)
 i   libmysqld-dev                             - MySQL embedded database development files
 p   libmysqld-dev:i386                        - MySQL embedded database development files
 p   libmysqld-pic                             - MySQL database development files
 p   libmysqld-pic:i386                        - MySQL database development files

这里是/usr/lib/mysql的内容

$ find /usr/lib/mysql
/usr/lib/mysql
/usr/lib/mysql/plugin
/usr/lib/mysql/plugin/qa_auth_client.so
/usr/lib/mysql/plugin/auth.so
/usr/lib/mysql/plugin/qa_auth_server.so
/usr/lib/mysql/plugin/semisync_master.so
/usr/lib/mysql/plugin/libdaemon_example.so
/usr/lib/mysql/plugin/ha_example.so
/usr/lib/mysql/plugin/adt_null.so
/usr/lib/mysql/plugin/auth_test_plugin.so
/usr/lib/mysql/plugin/auth_socket.so
/usr/lib/mysql/plugin/qa_auth_interface.so
/usr/lib/mysql/plugin/semisync_slave.so
/usr/lib/mysql/plugin/mypluglib.so

我不知道还能尝试什么，还能去哪里寻找，希望得到任何指点。

Answer 1

链接器标志应始终在最后指定:

gcc -D_FILE_OFFSET_BITS=64 `mysql_config --cflags` \
        -o check-my-ip \
        -s check-my-ip.c ../common/ini-file.c \
        `mysql_config --libs`