为什么通过将 /usr/lib 添加到 ld.so.conf 可以修复运行时未定义的符号？
我在 Linux 中有一个案例，其中 gcc 和 ld 干净地构建了东西，但在运行时我得到了一个未定义的符号（对于 libxerces-c.so.28 中的某些东西），由我自己的共享库之一在运行我的程序时报告。
第一个假设是缓存已损坏，最近安装了 xerces，或类似的东西，所以我运行了 ldconfig。没有修好。但是将 /usr/lib 添加到 ld.so.conf 然后运行 ldconfig 确实修复了它。
我的理解是/lib、/usr/lib，也许运行时动态链接器总是会搜索其他一两个位置。
??
（唯一不寻常的是，这是一个使用 jni 访问应用程序共享库的 java 程序。话又说回来，如果有什么合理的话，我应该在这个应用程序的过去 N 年里随时看到这个错误。）
I've got a case in linux where gcc and ld build things cleanly, but at runtime I get an undefined symbol (for something in libxerces-c.so.28), reported by one of my own shared libraries, when running my program.
First assumption was cache was broken, xerces recently installed, or something similar, so I ran ldconfig. Didn't fix it. But adding /usr/lib to ld.so.conf and then running ldconfig did fix it.
My understanding is /lib, /usr/lib, and perhaps one or two other spots are always searched by the run-time dynamic linker.
??
(The only thing out of the ordinary is this is a java program using jni to access application shared-libraries. Then again, if it were anything rational I should have seen this error any time in the past N years of this application.)
如果你对这篇内容有疑问，欢迎到本站社区发帖提问 参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。
绑定邮箱获取回复消息
由于您还没有绑定你的真实邮箱，如果其他用户或者作者回复了您的评论，将不能在第一时间通知您！
发布评论
评论（1）
在这种特殊情况下，该库位于 /usr/lib 中，但也位于另一个项目中（链接器首先找到该项目）。它一定是一个坏的/不完整的，因为它显然缺少一个符号。
我通过运行我的程序来解决这个问题，因为
这让我看到链接器挖掘不同的搜索路径，我看到它抓住了错误的路径。
哦 - 并且显式地将 /usr/lib 添加到 ld 配置中？这只是将 /usr/lib 放在搜索路径中比通常更早的位置，并且（运气好？）使 ld 在坏库之前找到好库。
In this particular case, the library was in /usr/lib, but also in with another project (and the linker was finding that one first). And it must have been a bad/incomplete one, since it was obviously missing a symbol.
I figured this out by running my program as
That let me watch the linker dig through the different search paths, and I saw it grab the wrong one.
Oh - and explicitly adding /usr/lib to the ld configuration? That just put /usr/lib earlier in the search path than it normally would have been, and (luck?) made ld find the good library before the bad one.