gfortran在Mac OS X 10.9(Mavericks)上不起作用

最近，我将OS X更新为10.9(小牛)；不幸的是，尽管我将OS X Mavericks的Xcode命令行更新为5.1.1，但gfortran停止工作.不久前，有人在此处提出了类似的问题，但我认为问题没有得到解决.

Recently, I updated my OS X to 10.9 (Mavericks); unfortunately, gfortran stops working although I updated Xcode command line to 5.1.1 for OS X Mavericks. Similar question has been asked sometime ago, here, but I don't think so the issue is sorted out.

这是我所做的:

首先，我删除了现有的gfortran

first I removed the existing gfortran

bash-3.2$ sudo rm -r /usr/local/gfortran /usr/local/bin/gfortran

然后我下载了gfortran-4.9-bin.tar，并将其解压缩并成功安装

Then I downloaded gfortran-4.9-bin.tar, and unzip it and installed successfully

bash-3.2$ gunzip gfortran-4.9-bin.tar

bash-3.2$ sudo tar xvf gfortran-4.9-bin.tar -C /

bash-3.2$ which gfortran     
/usr/local/bin/gfortran

但是当我开始运行代码时，出现以下错误，例如

but when I start running my codes , I got the following errors, e.g.

bash-3.2$ gfortran boolean1.f90

Undefined symbols for architecture x86_64:
      "_main", referenced from:
         implicit entry/start for main executable
    ld: symbol(s) not found for architecture x86_64
    collect2: error: ld returned 1 exit status

如果有人能指导我解决这个问题，我将非常感激.

I would be immensely grateful if anyone could guide me to solve this problem.