源码来自：UNP源码 intro目录下的daytimetcpcli.c
在编译时报错：
/tmp/ccB0LkJw.o: In function `main': daytimetcpcli.c:(.text+0x3d): undefined reference to `err_quit' daytimetcpcli.c:(.text+0x71): undefined reference to `err_sys' daytimetcpcli.c:(.text+0xeb): undefined reference to `err_quit' daytimetcpcli.c:(.text+0x11c): undefined reference to `err_sys' daytimetcpcli.c:(.text+0x15d): undefined reference to `err_sys' daytimetcpcli.c:(.text+0x1a2): undefined reference to `err_sys' collect2: error: ld returned 1 exit status原因： 没有找到error.c文件
解决：
gcc daytimetcpcli.c ../lib/error.c加上error.c 后编译可以得到a.out文件
