Linux：如何确定文件是否已被其他进程更新？

I am currently watching an XML file from log4j output. I have a custom viewer that displays the log-output in GUI. I need to watch this file as to when it gets updated so that the GUI can re-parse and update itself. In C# there is a FileWatcher concept so on Windows no-probs, but what options do i have using C on Linux.I am currently watching an XML file from log4j