pkg-config

pkg-config安装比较简单，Debian apt-get install pkg-config Mac brew install pkg-config

一般项目主要使用 pkg-config 的两个命令，例如opencv安装后，在Makefile中配置opencv的路径， pkg-config --cflags opencv 、pkg-config --libs opencv 来在编译阶段寻找opencv 的include 目录以及在链接阶段寻找libs目录

pkg-config 能够找到正确路径的前提是需要配置 $(progam).pc 文件，例如 pkg-config --cflags opencv 命令能正常工作的前提就是需要在pkg-config 的配置扫描路径下有 opencv.pc 文件

pkg-config 的默认扫描路径大概有这么几个地方： /usr/local/share/pkgconfig、 /usr/lib/pkgconfig、/usr/local/lib/pkgconfig 可通过pkg-config --variable pc_path pkg-config查询

有文档指出也能通过环境变量 PKG_CONFIG_PATH 进行指定，但是直接去默认扫描路径定义对应的.pc文件更直接

Mac 上brew安装的开发包一般会在/usr/local/lib/pkgconfig 下建立软链

.pc文件定义，可以直接参考pkg-config 的默认扫描路径下其他.pc文件的写法，或者参考下面的配置文件opencv.pc

prefix=/usr/local/Cellar/opencv/4.2.0_3
exec_prefix=${prefix}

Name: opencv
Description: Open source computer vision library
Requires:
Version: 4.2.0_3
Libs: ${prefix}/lib/libopencv_calib3d.dylib -lopencv_calib3d ${prefix}/lib/libopencv_core.dylib -lopencv_core ${prefix}/lib/libopencv_features2d.dylib -lopencv_features2d ${prefix}/lib/libopencv_flann.dylib -lopencv_flann ${prefix}/lib/libopencv_highgui.dylib -lopencv_highgui ${prefix}/lib/libopencv_imgproc.dylib -lopencv_imgproc  ${prefix}/lib/libopencv_ml.dylib -lopencv_ml ${prefix}/lib/libopencv_objdetect.dylib -lopencv_objdetect  ${prefix}/lib/libopencv_photo.dylib -lopencv_photo ${prefix}/lib/libopencv_stitching.dylib -lopencv_stitching ${prefix}/lib/libopencv_superres.dylib -lopencv_superres ${prefix}/lib/libopencv_video.dylib -lopencv_video ${prefix}/lib/libopencv_videostab.dylib -lopencv_videostab ${prefix}/lib/libopencv_imgcodecs.dylib -lopencv_imgcodecs 

Cflags: -I${prefix}/include/opencv4 -I${prefix}/include/opencv4/opencv2 -std=gnu++11