idle - make process 0 idle
idle() never returns for process 0, and always returns -1 for a user process.
Always, for a user process.
Since Linux 2.3.13, this system call does not exist anymore.
This function is Linux-specific, and should not be used in programs intended to be portable.
This page is part of release 4.15 of the Linux
man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.