proc_nice() changes the priority of the current process. If an error occurs, like the user lacks permission to change the priority, an error of level E_WARNING is generated and FALSE is returned. Otherwise, TRUE is returned.
Note: proc_nice() will only exist if your system has 'nice' capabilities. 'nice' conforms to: SVr4, SVID EXT, AT&T, X/OPEN, BSD 4.3. This means that proc_nice() is not available on Windows.
proc_nice() is not related to proc_open() and its associated functions in any way.