ld 找不到现有的库
我正在尝试在这个 Debian lenny 系统上将应用程序与 g++ 链接。 ld 抱怨找不到指定的库。 这里的具体示例是 ImageMagick，但我在使用其他一些库时也遇到了类似的问题。
我用以下命令调用链接器：
g++ -w (..lots of .o files/include directories/etc..) \
-L/usr/lib -lmagic
ld 抱怨：
/usr/bin/ld: cannot find -lmagic
但是，libmagic 存在：
$ locate libmagic.so
/usr/lib/libmagic.so.1
/usr/lib/libmagic.so.1.0.0
$ ls -all /usr/lib/libmagic.so.1*
lrwxrwxrwx 1 root root 17 2008-12-01 03:52 /usr/lib/libmagic.so.1 -> libmagic.so.1.0.0
-rwxrwxrwx 1 root root 84664 2008-09-09 00:05 /usr/lib/libmagic.so.1.0.0
$ ldd /usr/lib/libmagic.so.1.0.0
linux-gate.so.1 => (0xb7f85000)
libz.so.1 => /usr/lib/libz.so.1 (0xb7f51000)
libc.so.6 => /lib/i686/cmov/libc.so.6 (0xb7df6000)
/lib/ld-linux.so.2 (0xb7f86000)
$ sudo ldconfig -v | grep "libmagic"
libmagic.so.1 -> libmagic.so.1.0.0
如何进一步诊断此问题，可能出了什么问题？ 我在做一些完全愚蠢的事情吗？
I am attempting to link an application with g++ on this Debian lenny system. ld is complaining it cannot find specified libraries. The specific example here is ImageMagick, but I am having similar problems with a few other libraries too.
I am calling the linker with:
g++ -w (..lots of .o files/include directories/etc..) \
-L/usr/lib -lmagic
ld complains:
/usr/bin/ld: cannot find -lmagic
However, libmagic exists:
$ locate libmagic.so
/usr/lib/libmagic.so.1
/usr/lib/libmagic.so.1.0.0
$ ls -all /usr/lib/libmagic.so.1*
lrwxrwxrwx 1 root root 17 2008-12-01 03:52 /usr/lib/libmagic.so.1 -> libmagic.so.1.0.0
-rwxrwxrwx 1 root root 84664 2008-09-09 00:05 /usr/lib/libmagic.so.1.0.0
$ ldd /usr/lib/libmagic.so.1.0.0
linux-gate.so.1 => (0xb7f85000)
libz.so.1 => /usr/lib/libz.so.1 (0xb7f51000)
libc.so.6 => /lib/i686/cmov/libc.so.6 (0xb7df6000)
/lib/ld-linux.so.2 (0xb7f86000)
$ sudo ldconfig -v | grep "libmagic"
libmagic.so.1 -> libmagic.so.1.0.0
How do I diagnose this problem further, and what could be wrong? Am I doing something completely stupid?
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（9）
问题是链接器正在寻找
libmagic.so但你只有libmagic.so.1一个快速的技巧是符号链接
libmagic.so.1代码>到libmagic.soThe problem is the linker is looking for
libmagic.sobut you only havelibmagic.so.1A quick hack is to symlink
libmagic.so.1tolibmagic.so正如grepsedawk刚刚表述的那样，答案在于
g++的-l选项，调用ld。 如果您查看此命令的手册页，您可以执行以下操作：g++ -l:libmagic.so.1 [...]g++ -lmagic [...]，如果您的库路径中有一个名为 libmagic.so 的符号链接As just formulated by grepsedawk, the answer lies in the
-loption ofg++, callingld. If you look at the man page of this command, you can either do:g++ -l:libmagic.so.1 [...]g++ -lmagic [...], if you have a symlink named libmagic.so in your libs pathDebian 约定将共享库分为运行时组件 (
libmagic1: /usr/lib/libmagic.so.1 → libmagic.so.1.0.0) 及其开发组件 (libmagic) -dev: /usr/lib/libmagic.so → ...)。因为库的soname 是
libmagic.so.1，所以它是嵌入到可执行文件中的字符串，因此这是运行可执行文件时加载的文件。但是，由于该库被指定为链接器的
-lmagic，因此它会查找libmagic.so，这就是开发需要它的原因。请参阅 Diego E. Pettenò：链接器和名称，了解这一切在 Linux 上如何工作的详细信息。
简而言之，您应该
apt-get install libmagic-dev。 这不仅会为您提供libmagic.so，还会提供编译所需的其他文件，例如/usr/include/magic.h。It is Debian convention to separate shared libraries into their runtime components (
libmagic1: /usr/lib/libmagic.so.1 → libmagic.so.1.0.0) and their development components (libmagic-dev: /usr/lib/libmagic.so → …).Because the library's soname is
libmagic.so.1, that's the string that gets embedded into the executable so that's the file that is loaded when the executable is run.However, because the library is specified as
-lmagicto the linker, it looks forlibmagic.so, which is why it is needed for development.See Diego E. Pettenò: Linkers and names for details on how this all works on Linux.
In short, you should
apt-get install libmagic-dev. This will not only give youlibmagic.sobut also other files necessary for compiling like/usr/include/magic.h.在 Ubuntu 中，您可以安装 libtool 来自动解析库。
这为我解决了
ltdl的问题，它已作为libltdl.so.7安装，并且在以下位置中找不到简单的-lltdl品牌。In Ubuntu, you can install
libtoolwhich resolves the libraries automatically.This resolved a problem with
ltdlfor me, which had been installed aslibltdl.so.7and wasn't found as simply-lltdlin the make.如上所述，链接器正在寻找
libmagic.so，但您只有libmagic.so.1。要解决这个问题，只需执行更新缓存即可。
要验证您可以运行：
As mentioned above the linker is looking for
libmagic.so, but you only havelibmagic.so.1.To solve this problem just perform an update cache.
To verify you can run:
除非我严重错误
libmagic或-lmagic与 ImageMagick 不是同一个库。 您声明您想要 ImageMagick。ImageMagick 附带了一个实用程序，可为编译器提供所有适当的选项。
前任：
Unless I'm badly mistaken
libmagicor-lmagicis not the same library as ImageMagick. You state that you want ImageMagick.ImageMagick comes with a utility to supply all appropriate options to the compiler.
Ex:
从 Ubuntu 存储库安装 libgl1-mesa-dev 为我解决了这个问题。
Installing libgl1-mesa-dev from the Ubuntu repo resolved this problem for me.
我尝试了上面提到的所有解决方案，但没有一个解决了我的问题，但最后我用以下命令解决了它。
这会发挥魔法。
I tried all solutions mentioned above but none of them solved my issue but finally I solved it with the following command.
This will do the magic.
解决此问题的另一种方法是安装
-devel包。如果编译器正在寻找
libabc.so，而您有libabc.so.1，则需要安装-devel软件包，例如libabc-develaslibabc.so.1是一个运行时库，但libabc.so是一个开发库。Another way to solve this problem is to install the
-develpackage.If the compiler is looking for
libabc.sowhile you havelibabc.so.1, you need to install the-develpackage likelibabc-develaslibabc.so.1is a runtime lib butlibabc.sois a development lib.