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0: downtime 1: single-user mode, only root for Maintenance 2: multi-user, cannot use net file system3: full multi-user 5: Graphical 4: security mode 6: restart actually, you can view/etc/rc. rc * in d *. d .. Init 0, the corresponding system will run, the program specified in/etc/rc. d/rc0.d. Let's take a look at the name. [Root @ localhost ~] # Ls/etc/rc. d/rc0.d rj1_k35nmb K60crond 1_1_k88iscsi K90network 1_1_k35smb K66gpsd K75netfs K84NetworkManager 1_k88rsyslog 1_1_k20nfs 1_1_1_K75udev-post 1_1_1_1_1_1_k76openvpn K85mdmonitor K87alsasound K89netplugd unzip K30sendmail K50netconsole K74acpid K83bluetooth K85messagebus unzip K89rdisc K99lvm2-monitor according to the above red font, the two processes that open the opportunity to execute are killall and halt, both represent termination processes. Therefore, init 0 is used to indicate shutdown. Init 1, the corresponding system will run, the program specified in/etc/rc. d/rc1.d. [Root @ localhost ~] # Ls/etc/rc. d/commandid K35nmb K60crond %k84networkmanager %k88rsyslog %%k16ksm K35smb K66gpsd K75netfs %%%%%k20nfs %k76openvpn K85mdmonitor %%%%%%%%%k83bluetooth %% Nd K89rdisc S02lvm2-monitorK15gpm K30sendmail K50netconsole K74acpid K83portreserve K85rpcgssd K88iscsi K90network S26udev-post this level of startup services have three, udev, lvm related and single (single user mode services ). Therefore, the single-user mode is available only for root users, and other users are not supported. Init 2, the corresponding system will run, the program specified in/etc/rc. d/rc2.d. [Root @ localhost ~] # Ls/etc/rc. d/rc2.d/rjk20nfs 255.255.255.255.255.s23networkmanager 255.255.255.255.255.k75netfs 255.255.s12rsyslog 255.255.k30sendmail K50netconsole K76openvpn 255.k90network 255.s25cups 255.k66gpsd K83bluetooth K88iscsi S02lvm2-monitor. Or S26acpid unzip K35smb K69rpcsvcgssd unzip K89iscsid S08ip6tables S22messagebus S26udev-post S99alsasound this level of startup services more, NetworkManager/iptables/acpid/alsa have been enabled, but nfs, smb, openvpn-related services are not enabled. nfs is not supported at this level. Init 3, corresponding system run/etc/rc. d/rc3.d [root @ localhost ~] # Ls/etc/rc. d/rc3.d/~k30sendmail ~~~~~~~~~k76openvpn K90network S12rsyslog %s25netfs S50bluetooth %k50netconsole %K99lvm2-monitor S13iscsi %s26acpid %k66gpsd K85mdmonitor %s23networkmanager S2 6udev-post S84ksm unzip K69rpcsvcgssd K89netplugd S08ip6tables S14nfslock S24portreserve S30vboxdrv S85gpm S99alsasound this level of nfs service is enabled and becomes a full multi-user mode. Init 4 [root @ localhost ~] # Ls/etc/rc. d/rc4.d/javask30sendmail K66gpsd K85mdmonitor zookeeper S23NetworkManager S26udev-post zookeeper K35nmb zookeeper K35smb zookeeper S25cups zookeeper K76openvpn K90network S12rsyslog route S25netfs Protocol Th S90crondK25sshd K50netconsole K84wpa_supplicant K99lvm2-monitor S13iscsi S22messagebus S26acpid S50haldaemon S99alsasound this mode is called safe mode. Init 5 [root @ localhost ~] # Ls/etc/rc. d/rc5.d/commandid K66gpsd commandid K90network protocol S26udev-post S84ksm ?k30sendmail =k85mdmonitor K88iscsi K99lvm2-monitor S23NetworkManager ?##%%s25cups =k50netconsole K76openvpn =s08iptab Les S25netfs S50bluetooth S91smbK20nfs K60crond K83portreserve K86nfslock K89rdisc S12rsyslog S26acpid S50haldaemon S99alsasound complete graphics mode init 6 [root @ localhost ~] # Ls/etc/rc. d/rc6.d/commandid K35nmb K60crond zookeeper K88iscsi K90network zook16ksm K35smb K66gpsd K75netfs K84NetworkManager zook88rsyslog zookeeper K20nfs zookeeper Co., K75udev-post zookeeper K76openvpn Tor K87alsasound K89netplugd unzip K30sendmail K50netconsole K74acpid K83bluetooth K85messagebus unzip K89rdisc K99lvm2-monitor in this level, there are only two services, one is killall, one is reboot, that is, shut down the current system. This level is restart. Different system versions may have different files. If you want to view the files, you can refer to ll. In fact, they are all soft connections.
