启动级别:init 0,1,2,3,4,5,6

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     K76openvpn     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  K76openvpn      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  K76openvpn         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,openvpn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      K76openvpn         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      K76openvpn         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  K76openvpn      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     K76openvpn     K85mdmonitor      K87alsasound  K89netplugd  K98qemu

K15gpm        K30sendmail  K50netconsole  K74acpid       K83bluetooth   K85messagebus      K87rpcbind    K89rdisc     K99lvm2-mo