0:停机

1:单用户形式,只root进行维护

2:多用户,不能使用net file system

3:完全多用户

5:图形化

4:安全模式

6:重启 

其实,可以通过查看/etc/rc.d/中的rc*.d的文件来对比理解。。

init 0,对应的系统会运行,/etc/rc.d/rc0.d里指定的程序。我们来看下名称。

[root@localhost  ~]# ls /etc/rc.d/rc0.d 

K01dnsmasq    K15ksmtuned  K35nmb         K60crond       K74lm_sensors  K83portreserve    K85rpcgssd    K88iscsi     K90network       S00killall

K10cups       K16ksm       K35smb         K66gpsd        K75netfs       K84NetworkManager  K85rpcidmapd  K88rsyslog   K92ip6tables     S01halt

K10saslauthd  K20nfs       K36mysqld      K69rpcsvcgssd  K75udev-post   K84wpa_supplicant  K86nfslock    K89iscsid    K92iptables

K10xfs        K25sshd      K50haldaemon   K70vboxdrv     K76open***     K85mdmonitor      K87alsasound  K89netplugd  K98qemu

K15gpm        K30sendmail  K50netconsole  K74acpid       K83bluetooth   K85messagebus      K87rpcbind    K89rdisc     K99lvm2-monitor

依照上述红色字体,开机会执行的两个进程是killall和halt,这两个都表示为终止进程。故init 0是用于表示关机的。

init 1,对应的系统会运行,/etc/rc.d/rc1.d里指定的程序。

[root@localhost ~] # ls /etc/rc.d/rc1.d

K01dnsmasq    K15ksmtuned  K35nmb         K60crond       K74lm_sensors   K84NetworkManager  K85rpcidmapd  K88rsyslog   K92ip6tables     S99single

K10cups       K16ksm       K35smb         K66gpsd        K75netfs        K84wpa_supplicant  K86nfslock    K89iscsid    K92iptables

K10saslauthd  K20nfs       K36mysqld      K69rpcsvcgssd  K76open***      K85mdmonitor      K87alsasound  K89netplugd  K98qemu

K10xfs        K25sshd      K50haldaemon   K70vboxdrv     K83bluetooth    K85messagebus      K87rpcbind    K89rdisc     S02lvm2-monitor

K15gpm        K30sendmail  K50netconsole  K74acpid       K83portreserve  K85rpcgssd        K88iscsi      K90network   S26udev-post

这个级别启动的服务有三个,udev、lvm相关的和single(单用户模式的服务)。故此级别是单用户模式,只有root能用,不支持其他用户。

init 2,对应的系统会运行,/etc/rc.d/rc2.d里指定的程序。

[root@localhost ~ ]# ls /etc/rc.d/rc2.d/

K01dnsmasq    K20nfs       K36mysqld      K74lm_sensors      K85rpcgssd    K89netplugd      S08iptables    S23NetworkManager  S30vboxdrv    S99local

K10saslauthd  K25sshd      K50haldaemon   K75netfs           K85rpcidmapd  K89rdisc        S12rsyslog     S24portreserve     S35qemu

K10xfs        K30sendmail  K50netconsole  K76open***         K86nfslock    K90network      S13rpcbind     S25cups            S85gpm

K15ksmtuned   K35nmb       K66gpsd        K83bluetooth       K88iscsi      S02lvm2-monitor  S15mdmonitor   S26acpid           S90crond

K16ksm        K35smb       K69rpcsvcgssd  K84wpa_supplicant  K89iscsid     S08ip6tables    S22messagebus  S26udev-post       S99alsasound

这个级别启动的服务多了,NetworkManager/iptables/acpid/alsa都已经开启,但是nfs,smb,open***相关服务没有开启,这个级别不支持nfs。

init 3 , 对应的系统运行/etc/rc.d/rc3.d

[root@localhost ~] # ls /etc/rc.d/rc3.d/

K01dnsmasq    K30sendmail    K74lm_sensors      K89rdisc         S08iptables  S18rpcidmapd      S25cups       S35qemu       S85ksmtuned   S99local

K10saslauthd  K36mysqld      K76open***         K90network       S12rsyslog   S19rpcgssd        S25netfs      S50bluetooth  S90crond

K10xfs        K50netconsole  K84wpa_supplicant  K99lvm2-monitor  S13iscsi     S22messagebus      S26acpid      S50haldaemon  S91nmb

K20nfs        K66gpsd        K85mdmonitor       S07iscsid        S13rpcbind   S23NetworkManager  S26udev-post  S84ksm        S91smb

K25sshd       K69rpcsvcgssd  K89netplugd        S08ip6tables     S14nfslock   S24portreserve    S30vboxdrv    S85gpm        S99alsasound

这个级别nfs服务是开启的,被成为完全多用户模式。

init 4

[root@localhost ~ ]# ls /etc/rc.d/rc4.d/

K01dnsmasq    K30sendmail    K66gpsd            K85mdmonitor     S07iscsid     S13rpcbind    S23NetworkManager  S26udev-post  S84ksm        S99local

K10saslauthd  K35nmb         K69rpcsvcgssd      K89netplugd      S08ip6tables  S14nfslock    S24portreserve     S30vboxdrv    S85gpm

K10xfs        K35smb         K74lm_sensors      K89rdisc         S08iptables   S18rpcidmapd  S25cups            S35qemu       S85ksmtuned

K20nfs        K36mysqld      K76open***         K90network       S12rsyslog    S19rpcgssd    S25netfs           S50bluetooth  S90crond

K25sshd       K50netconsole  K84wpa_supplicant  K99lvm2-monitor  S13iscsi      S22messagebus  S26acpid           S50haldaemon  S99alsasound

 此模式被称为安全模式。

init 5

[root@localhost ~ ]# ls /etc/rc.d/rc5.d/

K01dnsmasq    K25sshd        K66gpsd         K84wpa_supplicant  K87rpcbind   K90network      S22messagebus      S26udev-post  S84ksm        S99local

K10saslauthd  K30sendmail    K69rpcsvcgssd   K85mdmonitor       K88iscsi     K99lvm2-monitor  S23NetworkManager  S30vboxdrv    S85ksmtuned

K10xfs        K36mysqld      K74lm_sensors   K85rpcgssd         K89iscsid    S08ip6tables    S25cups            S35qemu       S91nmb

K15gpm        K50netconsole  K76open***      K85rpcidmapd       K89netplugd  S08iptables      S25netfs           S50bluetooth  S91smb

K20nfs        K60crond       K83portreserve  K86nfslock         K89rdisc     S12rsyslog      S26acpid           S50haldaemon  S99alsasound

完整的图形模式

init 6

[root@localhost ~ ]# ls /etc/rc.d/rc6.d/

K01dnsmasq    K15ksmtuned  K35nmb         K60crond       K74lm_sensors  K83portreserve    K85rpcgssd    K88iscsi     K90network       S00killall

K10cups       K16ksm       K35smb         K66gpsd        K75netfs       K84NetworkManager  K85rpcidmapd  K88rsyslog   K92ip6tables     S01reboot

K10saslauthd  K20nfs       K36mysqld      K69rpcsvcgssd  K75udev-post   K84wpa_supplicant  K86nfslock    K89iscsid    K92iptables

K10xfs        K25sshd      K50haldaemon   K70vboxdrv     K76open***     K85mdmonitor      K87alsasound  K89netplugd  K98qemu

K15gpm        K30sendmail  K50netconsole  K74acpid       K83bluetooth   K85messagebus      K87rpcbind    K89rdisc     K99lvm2-monitor

这个级别里,只有两个服务,一个为killall,一个是reboot,即,关闭现在的系统,重启。故此级别是重启。