CentOS启动级别:init 0,1,2,3,4,5,6

分类:CentOS教程 阅读:1909 次

这是个很久的知识点了,只是自己一直都迷迷糊糊的,今天在翻出来好好理解下。。

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

K01dnsmasqK15ksmtunedK35nmbK60crondK74lm_sensorsK83portreserveK85rpcgssdK88iscsiK90networkS00killall

K10cupsK16ksmK35smbK66gpsdK75netfsK84NetworkManagerK85rpcidmapdK88rsyslogK92ip6tablesS01halt

K10saslauthdK20nfsK36mysqldK69rpcsvcgssdK75udev-postK84wpa_supplicantK86nfslockK89iscsidK92iptables

K10xfsK25sshdK50haldaemonK70vboxdrvK76openvpnK85mdmonitorK87alsasoundK89netplugdK98qemu

K15gpmK30sendmailK50netconsoleK74acpidK83bluetoothK85messagebusK87rpcbindK89rdiscK99lvm2-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

K01dnsmasqK15ksmtunedK35nmbK60crondK74lm_sensorsK84NetworkManagerK85rpcidmapdK88rsyslogK92ip6tablesS99single

K10cupsK16ksmK35smbK66gpsdK75netfsK84wpa_supplicantK86nfslockK89iscsidK92iptables

K10saslauthdK20nfsK36mysqldK69rpcsvcgssdK76openvpnK85mdmonitorK87alsasoundK89netplugdK98qemu

K10xfsK25sshdK50haldaemonK70vboxdrvK83bluetoothK85messagebusK87rpcbindK89rdiscS02lvm2-monitor

K15gpmK30sendmailK50netconsoleK74acpidK83portreserveK85rpcgssdK88iscsiK90networkS26udev-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/

K01dnsmasqK20nfsK36mysqldK74lm_sensorsK85rpcgssdK89netplugdS08iptablesS23NetworkManagerS30vboxdrvS99local

K10saslauthdK25sshdK50haldaemonK75netfsK85rpcidmapdK89rdiscS12rsyslogS24portreserveS35qemu

K10xfsK30sendmailK50netconsoleK76openvpnK86nfslockK90networkS13rpcbindS25cupsS85gpm

K15ksmtunedK35nmbK66gpsdK83bluetoothK88iscsiS02lvm2-monitorS15mdmonitorS26acpidS90crond

K16ksmK35smbK69rpcsvcgssdK84wpa_supplicantK89iscsidS08ip6tablesS22messagebusS26udev-postS99alsasound

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/

K01dnsmasqK30sendmailK74lm_sensorsK89rdiscS08iptablesS18rpcidmapdS25cupsS35qemuS85ksmtunedS99local

K10saslauthdK36mysqldK76openvpnK90networkS12rsyslogS19rpcgssdS25netfsS50bluetoothS90crond

K10xfsK50netconsoleK84wpa_supplicantK99lvm2-monitorS13iscsiS22messagebusS26acpidS50haldaemonS91nmb

K20nfsK66gpsdK85mdmonitorS07iscsidS13rpcbindS23NetworkManagerS26udev-postS84ksmS91smb

K25sshdK69rpcsvcgssdK89netplugdS08ip6tablesS14nfslockS24portreserveS30vboxdrvS85gpmS99alsasound

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/

K01dnsmasqK30sendmailK66gpsdK85mdmonitorS07iscsidS13rpcbindS23NetworkManagerS26udev-postS84ksmS99local

K10saslauthdK35nmbK69rpcsvcgssdK89netplugdS08ip6tablesS14nfslockS24portreserveS30vboxdrvS85gpm

K10xfsK35smbK74lm_sensorsK89rdiscS08iptablesS18rpcidmapdS25cupsS35qemuS85ksmtuned

K20nfsK36mysqldK76openvpnK90networkS12rsyslogS19rpcgssdS25netfsS50bluetoothS90crond

K25sshdK50netconsoleK84wpa_supplicantK99lvm2-monitorS13iscsiS22messagebusS26acpidS50haldaemonS99alsasound

此模式被称为安全模式。

init 5

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

K01dnsmasqK25sshdK66gpsdK84wpa_supplicantK87rpcbindK90networkS22messagebusS26udev-postS84ksmS99local

K10saslauthdK30sendmailK69rpcsvcgssdK85mdmonitorK88iscsiK99lvm2-monitorS23NetworkManagerS30vboxdrvS85ksmtuned

K10xfsK36mysqldK74lm_sensorsK85rpcgssdK89iscsidS08ip6tablesS25cupsS35qemuS91nmb

K15gpmK50netconsoleK76openvpnK85rpcidmapdK89netplugdS08iptablesS25netfsS50bluetoothS91smb

K20nfsK60crondK83portreserveK86nfslockK89rdiscS12rsyslogS26acpidS50haldaemonS99alsasound

完整的图形模式

init 6

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

K01dnsmasqK15ksmtunedK35nmbK60crondK74lm_sensorsK83portreserveK85rpcgssdK88iscsiK90networkS00killall

K10cupsK16ksmK35smbK66gpsdK75netfsK84NetworkManagerK85rpcidmapdK88rsyslogK92ip6tablesS01reboot

K10saslauthdK20nfsK36mysqldK69rpcsvcgssdK75udev-postK84wpa_supplicantK86nfslockK89iscsidK92iptables

K10xfsK25sshdK50haldaemonK70vboxdrvK76openvpnK85mdmonitorK87alsasoundK89netplugdK98qemu

K15gpmK30sendmailK50netconsoleK74acpidK83bluetoothK85messagebusK87rpcbindK89rdiscK99lvm2-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。

不同的系统版本,可能里面的文件会不同,如果要查看,可以通过ll来看,其实他们都是软连接。