makefile的杂七杂八

-fPIC -shared 生成动态链接库 .so
ar rc 生成静态连接库 .a

参数:“-I”（大写i），“-L”（大写l），“-l”（小写l）
例：
gcc -o hello hello.c -I /home/hello/include -L /home/hello/lib -lworld

表示在编译hello.c时：

-I /home/hello/include表示将/home/hello/include目录作为第一个寻找头文件的目录，寻找的顺序是：/home/hello/include-->/usr/include-->/usr/local/include

-L /home/hello/lib表示将/home/hello/lib目录作为第一个寻找库文件的目录，寻找的顺序是：/home/hello/lib-->/lib-->/usr/lib-->/usr/local/lib

-lworld表示在上面的lib的路径中寻找libworld.so动态库文件（如果gcc编译选项中加入了“-static”表示寻找libworld.a静态库文件）

关于 -pthread和-lpthread

$ man gcc | grep pthread           -mvxworks -G num -pthread           -mno-unaligned-doubles -mv8plus -mno-v8plus -mvis -mno-vis -threads -pthreads           -pthread           implies -pthread, and thus is only supported on targets that have support for           -pthread.           implies -pthread, and thus is only supported on targets that have support for           -pthread.           option and the -pthread option are incompatible.       -pthread           Adds support for multithreading with the pthreads library. This option sets flags for       -pthreads       -pthread           This is a synonym for -pthreads. $ man gcc | grep lpthread $

gcc 4.5.2中已经没有了关于 -lpthread的介绍了。所以以后的多线程编译应该用-pthread，而不是-lpthread。