解决OpenCV4出现“/usr/bin/ld:cannot find -lcudart_static.../usr/bin/ld: cannot find -lx86

Ubuntu18.04解决OpenCV4出现“/usr/bin/ld: cannot find -lcudart_static.../usr/bin/ld: cannot find -lx86_64-linux-gnu”问题

问题描述
问题定位
尝试方法
终极方法
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问题描述

安装完成OpenCV4.3.0后，在编译示例时遇到如下问题：

具体描述如下：

g++ example.cpp -o example.o -std=c++11 -c -Wall -I/home/brainiac/Program/opencv4/include/opencv4/opencv -I/home/brainiac/Program/opencv4/include/opencv4
g++ example.o -o opencv_example -L/home/brainiac/Program/opencv4/lib -L-L/usr/local/cuda-10.1 -L-L/usr/lib -lopencv_gapi -lopencv_stitching -lopencv_alphamat -lopencv_aruco -lopencv_bgsegm -lopencv_bioinspired -lopencv_ccalib -lopencv_cudabgsegm -lopencv_cudafeatures2d -lopencv_cudaobjdetect -lopencv_cudastereo -lopencv_cvv -lopencv_dnn_objdetect -lopencv_dnn_superres -lopencv_dpm -lopencv_highgui -lopencv_face -lopencv_freetype -lopencv_fuzzy -lopencv_hdf -lopencv_hfs -lopencv_img_hash -lopencv_intensity_transform -lopencv_line_descriptor -lopencv_quality -lopencv_rapid -lopencv_reg -lopencv_rgbd -lopencv_saliency -lopencv_sfm -lopencv_stereo -lopencv_structured_light -lopencv_phase_unwrapping -lopencv_superres -lopencv_cudacodec -lopencv_surface_matching -lopencv_tracking -lopencv_datasets -lopencv_text -lopencv_dnn -lopencv_plot -lopencv_videostab -lopencv_cudaoptflow -lopencv_optflow -lopencv_cudalegacy -lopencv_videoio -lopencv_cudawarping -lopencv_xfeatures2d -lopencv_shape -lopencv_ml -lopencv_ximgproc -lopencv_video -lopencv_xobjdetect -lopencv_objdetect -lopencv_calib3d -lopencv_imgcodecs -lopencv_features2d -lopencv_flann -lopencv_xphoto -lopencv_photo -lopencv_cudaimgproc -lopencv_cudafilters -lopencv_imgproc -lopencv_cudaarithm -lopencv_core -lopencv_cudev -lm -lpthread -lGL -lGLU -lcudart_static -ldl -lrt -lnppc -lnppial -lnppicc -lnppicom -lnppidei -lnppif -lnppig -lnppim -lnppist -lnppisu -lnppitc -lnpps -lcublas -lcudnn -lcufft -llib64 -lx86_64-linux-gnu
/usr/bin/ld: cannot find -lcudart_static
/usr/bin/ld: cannot find -lnppc
/usr/bin/ld: cannot find -lnppial
/usr/bin/ld: cannot find -lnppicc
/usr/bin/ld: cannot find -lnppicom
/usr/bin/ld: cannot find -lnppidei
/usr/bin/ld: cannot find -lnppif
/usr/bin/ld: cannot find -lnppig
/usr/bin/ld: cannot find -lnppim
/usr/bin/ld: cannot find -lnppist
/usr/bin/ld: cannot find -lnppisu
/usr/bin/ld: cannot find -lnppitc
/usr/bin/ld: cannot find -lnpps
/usr/bin/ld: cannot find -lcudnn
/usr/bin/ld: cannot find -lcufft
/usr/bin/ld: cannot find -llib64
/usr/bin/ld: cannot find -lx86_64-linux-gnu
collect2: error: ld returned 1 exit status
Makefile:8: recipe for target 'opencv_example' failed
make: *** [opencv_example] Error 1

本来应该写在安装过程中分享，但是这个问题太坑了，网上搜了半天没找到解决办法（有一个类似的问题，下面会说明），因此另拿出来分享一下。

问题定位

通过观察发现全是静态库的问题，而OpenCV4是根据opencv4.pc查找相应头和库。
因此根据自己的安装位置找到opencv4.pc文件，查看该文件。

#<open_path>/lib/pkgconfig/opencv4.pc
#比如安装在/usr/local/opencv4下：
$ sudo vim /usr/local/opencv4/lib/pkgconfig/opencv4.pc

尝试方法

找到一个解决方法是，修改CUDA的库链接目录：
文件最后的"-L-L/usr/local/cuda-10.1"修改为"-L/usr/local/cuda-10.1/lib64"，其中"/usr/local/cuda-10.1"是安装CUDA的目录，改为自己安装的路径即可，如下所示:

这个方法的确部分的解决了问题，重新make示例文件时解决了部分库依赖报错问题，报错信息变为：

g++ example.cpp -o example.o -std=c++11 -c -Wall -I/home/brainiac/Program/opencv4/include/opencv4/opencv -I/home/brainiac/Program/opencv4/include/opencv4
g++ example.o -o opencv_example -L/home/brainiac/Program/opencv4/lib -L-L/usr/local/cuda-10.1 -L-L/usr/lib -lopencv_gapi -lopencv_stitching -lopencv_alphamat -lopencv_aruco -lopencv_bgsegm -lopencv_bioinspired -lopencv_ccalib -lopencv_cudabgsegm -lopencv_cudafeatures2d -lopencv_cudaobjdetect -lopencv_cudastereo -lopencv_cvv -lopencv_dnn_objdetect -lopencv_dnn_superres -lopencv_dpm -lopencv_highgui -lopencv_face -lopencv_freetype -lopencv_fuzzy -lopencv_hdf -lopencv_hfs -lopencv_img_hash -lopencv_intensity_transform -lopencv_line_descriptor -lopencv_quality -lopencv_rapid -lopencv_reg -lopencv_rgbd -lopencv_saliency -lopencv_sfm -lopencv_stereo -lopencv_structured_light -lopencv_phase_unwrapping -lopencv_superres -lopencv_cudacodec -lopencv_surface_matching -lopencv_tracking -lopencv_datasets -lopencv_text -lopencv_dnn -lopencv_plot -lopencv_videostab -lopencv_cudaoptflow -lopencv_optflow -lopencv_cudalegacy -lopencv_videoio -lopencv_cudawarping -lopencv_xfeatures2d -lopencv_shape -lopencv_ml -lopencv_ximgproc -lopencv_video -lopencv_xobjdetect -lopencv_objdetect -lopencv_calib3d -lopencv_imgcodecs -lopencv_features2d -lopencv_flann -lopencv_xphoto -lopencv_photo -lopencv_cudaimgproc -lopencv_cudafilters -lopencv_imgproc -lopencv_cudaarithm -lopencv_core -lopencv_cudev -lm -lpthread -lGL -lGLU -lcudart_static -ldl -lrt -lnppc -lnppial -lnppicc -lnppicom -lnppidei -lnppif -lnppig -lnppim -lnppist -lnppisu -lnppitc -lnpps -lcublas -lcudnn -lcufft -llib64 -lx86_64-linux-gnu
/usr/bin/ld: cannot find -llib64
/usr/bin/ld: cannot find -lx86_64-linux-gnu
collect2: error: ld returned 1 exit status
Makefile:8: recipe for target 'opencv_example' failed
make: *** [opencv_example] Error 1

仅剩下，llib64和lx86_64-linux-gnu，然后还是按着这个库文件依赖这个方向查找，但是没有任何这两个库的信息，甚至卸载重装了若干次。

终极方法

在观察了opencv4.pc的结构后，最后决定破釜沉舟。
上面方法证明了一个-L可以解决一定问题，同时只要将-llib64与前面合并就可以构造出所需路径。因此将opencv4.pc最后部分修改为以下内容：

简单来讲就是将opencv4.pcwen文件中"-L-L/usr/local/cuda-10.1 -llib64 -L-L/usr/lib -lx86_64-linux-gnu"修改为"-L/usr/local/cuda-10.1/lib64 -L/usr/lib/x86_64-linux-gnu".
再次编译示例成功运行，暂时没有发现有什么不妥的地方，如果有什么问题再议。

但是没有人遇到这个问题吗？是因为我安装路径太奇怪装在/home目录下？但是也试了装在/usr/lib下还是这个问题。

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希望有所帮助，enjoy coding.