问题解决

• 提示错误

$ cc -shared -o libex29.so libex29.o
/usr/bin/ld: libex29.o: relocation R_X86_64_32 against `.rodata' 
can not be used when making a shared object; 
recompile with -fPIC
libex29.o: error adding symbols: Bad value
collect2: error: ld returned 1 exit status

• 解决方法 : 添加-fPIC参数

$ cc -fPIC -c libex29.c -o libex29.o
$ cc -shared -o libex29.so libex29.o

$ ls
dbg.h  ex29.c  libex29.c  libex29.o  libex29.so

参考资料

• Linux共享对象之编译参数fPIC
  https://www.cnblogs.com/cswuyg/p/3830703.html