proc_nice() changes the priority of the current process by the amount specified in increment. A positive increment will lower the priority of the current process, whereas a negative increment will raise the priority.
proc_nice() is not related to proc_open() and its associated functions in any way.
如果成功则返回 TRUE,失败则返回 FALSE。 If an error occurs, like the user lacks permission to change the priority, an error of level E_WARNING is also generated.