apue 在 mac 环境编译错误

参考资料：https://unix.stackexchange.com/questions/105483/compiling-code-from-apue

笔者使用 mac 学习 apue， 在编译的时候出现错误，错误如下：

Undefined symbols for architecture x86_64:
  "_TELL_CHILD", referenced from:
      _main in 14_5-4244a7.o
  "_TELL_PARENT", referenced from:
      _main in 14_5-4244a7.o
  "_TELL_WAIT", referenced from:
      _main in 14_5-4244a7.o
  "_WAIT_CHILD", referenced from:
      _main in 14_5-4244a7.o
  "_WAIT_PARENT", referenced from:
      _main in 14_5-4244a7.o
  "_err_sys", referenced from:
      _lock_test in 14_5-4244a7.o
      _main in 14_5-4244a7.o
      _lockabyte in 14_5-4244a7.o
  "_lock_reg", referenced from:
      _lockabyte in 14_5-4244a7.o
ld: symbol(s) not found for architecture x86_64

在解决该问题时浪费很多时间，记下解决办法，希望可以帮助到你。

前提：已经正确安装 apue，安装方法自行搜索，路径如下：

DilldeMacBook-Pro:apue.3e dill$ pwd
/Users/dill/Downloads/apue.3e
DilldeMacBook-Pro:apue.3e dill$ cp include/* /usr/local/include/
DilldeMacBook-Pro:apue.3e dill$ cp lib/* /usr/local/lib/

避免上文的编译错误，采用如下命令编译：

gcc -o myls myls.c -I /usr/local/include -L /usr/local/lib/ -lapue

myls.c 为需要编译的 C 文件

-I 为 gcc 指定 include 地址

-L 为 gcc 指定 library 地址

-lapue 指定在 lib 文件夹中  library 文件名（"/usr/local/lib/libapue.a"）

-LXXX means to look for a file in the library directory with the name: libXXX.a or libXXX.so.