Linux 7 boot Levels and Rc.local__linux

There are 7 levels of startup in Linux

Run Level 0: System shutdown status, system default run level can not be set to 0, otherwise it will not start running Level 1: Single user working status, root permissions, for system maintenance, prohibit remote login run Level 2: Multiuser status (no NFS) run Level 3: Full multiuser State (with NFS), Login to console command line mode run Level 4: System not used, keep running level 5:x11 console, login to GUI mode run Level 6: System shuts down and restarts, the default run level cannot be set to 6, otherwise it will not start normally

Under/ETC/RC.D, there are 7 directories named RCN.D, corresponding to the 7 running levels of the system

The system will enter the corresponding RCN.D directory according to the specified run level, and retrieve the linked files in the directory according to the file name sequence. For files that start with K, the system will terminate the corresponding service for files that begin with S, the system will start the corresponding service

Where Rc.sysinit is a system initialization script, Rc.local is a file that is customized for the user to execute at startup.