关于file.lock一问

我在用ansys调用我得apdl编写的文件时总是出现下面的提示，请问如何加一条命令避免这个呀。  
我删除file.lock就可以算了，只是每次都这样，太麻烦.  
*** ERROR ***  
Another ANSYS job with the same job name (file) is already running in this  
directory or the file.lock file has not been deleted from an abnormally  
terminated ANSYS run. To disable this check, set the ANSYS_LOCK environment  
variable to OFF.

我在帮助里面看见下面的话  
ANSYS_LOCK - set to ON (default) to create file locks to prevent users from opening a new job with the same name and in the same directory as the current job.  
但不知道如何设置：（