1.运行级别一共分为7个
1.1 查看7个运行级别配置文件
[root@test6 ~]# ls /etc/rc.d/ init.d rc rc0.d rc1.d rc2.d rc3.d rc4.d rc5.d rc6.d rc.local rc.sysinit
1.2.0 运行级别0.文件中 K 开头的代表不能运行，S开头代表可以运行，我们可以看到，只能运行关机命令
[root@test6 ~]# ls /etc/rc.d/rc0.d/ K01dnsmasq K05saslauthd K30sendmail K74haldaemon K87mcstrans K89netplugd K95kudzu K01smartd K10cups K44rawdevices K74nscd K87multipathd K89pand K99cpuspeed K02avahi-daemon K10psacct K50ibmasm K75netfs K87portmap K89rdisc K99lvm2-monitor K02avahi-dnsconfd K10tcsd K50netconsole K85mdmonitor K87restorecond K90bluetooth K99microcode_ctl K02NetworkManager K10xfs K60crond K85mdmpd K88auditd K90network K99readahead_early K02oddjobd K15gpm K69rpcsvcgssd K85messagebus K88pcscd K91capi K99readahead_later K03yum-updatesd K15httpd K72autofs K85rpcgssd K88syslog K91isdn S00killall K05anacron K20nfs K73ypbind K85rpcidmapd K88wpa_supplicant K92ip6tables S01halt K05atd K24irda K74acpid K86nfslock K89dund K92iptables K05conman K25sshd K74apmd K87irqbalance K89hidd K95firstboot
1.2.1 运行级别1. 单用户工作状态，拥有root权限，用于系统维护，禁止远程登录。
[root@test6 ~]# ls /etc/rc.d/rc1.d/ K01dnsmasq K05saslauthd K30sendmail K74haldaemon K87mcstrans K89netplugd K95kudzu K01smartd K10cups K44rawdevices K74nscd K87multipathd K89pand K99microcode_ctl K02avahi-daemon K10psacct K50ibmasm K75netfs K87portmap K89rdisc K99readahead_early K02avahi-dnsconfd K10tcsd K50netconsole K85mdmonitor K87restorecond K90bluetooth K99readahead_later K02NetworkManager K10xfs K60crond K85mdmpd K88auditd K90network S02lvm2-monitor K02oddjobd K15gpm K69rpcsvcgssd K85messagebus K88pcscd K91capi S13cpuspeed K03yum-updatesd K15httpd K72autofs K85rpcgssd K88syslog K91isdn S99single K05anacron K20nfs K73ypbind K85rpcidmapd K88wpa_supplicant K92ip6tables K05atd K24irda K74acpid K86nfslock K89dund K92iptables K05conman K25sshd K74apmd K87irqbalance K89hidd K95firstboot
1.2.2 运行级别2.多用户状态，没有(NFS)
[root@test6 ~]# ls /etc/rc.d/rc2.d/ K01dnsmasq K15httpd K74nscd K89dund S04readahead_early S13irqbalance S85gpm K02avahi-daemon K20nfs K75netfs K89netplugd S08ip6tables S15mdmonitor S90crond K02avahi-dnsconfd K24irda K85mdmpd K89pand S08iptables S25bluetooth S90xfs K02NetworkManager K44rawdevices K85messagebus K89rdisc S08mcstrans S25pcscd S95anacron K02oddjobd K50ibmasm K85rpcgssd K91capi S09isdn S26acpid S97yum-updatesd K05atd K50netconsole K85rpcidmapd K95firstboot S10network S26apmd S99local K05conman K69rpcsvcgssd K86nfslock K95kudzu S11auditd S26hidd S99smartd K05saslauthd K72autofs K87multipathd K99readahead_later S12restorecond S55sshd K10psacct K73ypbind K87portmap S00microcode_ctl S12syslog S56cups K10tcsd K74haldaemon K88wpa_supplicant S02lvm2-monitor S13cpuspeed S80sendmail
1.2.3 运行级别3.完全的多用户状态，登录以后进入控制台命令模式。这个时候也可以使用图形化，命令 startx 开启图形化桌面，但是级别还是3
[root@test6 ~]# ls /etc/rc.d/rc3.d/ K01dnsmasq K24irda K89netplugd S08iptables S14nfslock S26haldaemon S95anacron K02avahi-dnsconfd K50ibmasm K89pand S08mcstrans S15mdmonitor S26hidd S95atd K02NetworkManager K50netconsole K89rdisc S09isdn S18rpcidmapd S28autofs S97yum-updatesd K02oddjobd K69rpcsvcgssd K91capi S10network S19rpcgssd S55sshd S98avahi-daemon K05conman K73ypbind K99readahead_later S11auditd S22messagebus S56cups S99firstboot K05saslauthd K74nscd S00microcode_ctl S12restorecond S25bluetooth S56rawdevices S99local K10psacct K85mdmpd S02lvm2-monitor S12syslog S25netfs S80sendmail S99smartd K10tcsd K87multipathd S04readahead_early S13cpuspeed S25pcscd S85gpm K15httpd K88wpa_supplicant S05kudzu S13irqbalance S26acpid S90crond K20nfs K89dund S08ip6tables S13portmap S26apmd S90xfs
1.2.4 运行级别4.系统保留，未使用
[root@test6 ~]# ls /etc/rc.d/rc4.d/ K01dnsmasq K24irda K89netplugd S08ip6tables S13portmap S26apmd S90xfs K02avahi-dnsconfd K50ibmasm K89pand S08iptables S14nfslock S26haldaemon S95anacron K02NetworkManager K50netconsole K89rdisc S08mcstrans S15mdmonitor S26hidd S95atd K02oddjobd K69rpcsvcgssd K91capi S09isdn S18rpcidmapd S28autofs S97yum-updatesd K05conman K73ypbind K95firstboot S10network S19rpcgssd S55sshd S98avahi-daemon K05saslauthd K74nscd K99readahead_later S11auditd S22messagebus S56cups S99local K10psacct K85mdmpd S00microcode_ctl S12restorecond S25bluetooth S56rawdevices S99smartd K10tcsd K87multipathd S02lvm2-monitor S12syslog S25netfs S80sendmail K15httpd K88wpa_supplicant S04readahead_early S13cpuspeed S25pcscd S85gpm K20nfs K89dund S05kudzu S13irqbalance S26acpid S90crond
1.2.5 运行级别5.X11登录台，登录后进入图形GUI模式
[root@test6 ~]# ls /etc/rc.d/rc5.d/ K01dnsmasq K24irda K89netplugd S08mcstrans S15mdmonitor S26hidd S95atd K02avahi-dnsconfd K50ibmasm K89pand S09isdn S18rpcidmapd S28autofs S96readahead_later K02NetworkManager K50netconsole K89rdisc S10network S19rpcgssd S55sshd S97yum-updatesd K02oddjobd K69rpcsvcgssd K91capi S11auditd S22messagebus S56cups S98avahi-daemon K05conman K73ypbind S00microcode_ctl S12restorecond S25bluetooth S56rawdevices S99firstboot K05saslauthd K74nscd S02lvm2-monitor S12syslog S25netfs S80sendmail S99local K10psacct K85mdmpd S04readahead_early S13cpuspeed S25pcscd S85gpm S99smartd K10tcsd K87multipathd S05kudzu S13irqbalance S26acpid S90crond K15httpd K88wpa_supplicant S08ip6tables S13portmap S26apmd S90xfs K20nfs K89dund S08iptables S14nfslock S26haldaemon S95anacron
1.2.6 运行级别6.正常关闭并重启
[root@test6 ~]# ls /etc/rc.d/rc6.d/ K01dnsmasq K05saslauthd K30sendmail K74haldaemon K87mcstrans K89netplugd K95kudzu K01smartd K10cups K44rawdevices K74nscd K87multipathd K89pand K99cpuspeed K02avahi-daemon K10psacct K50ibmasm K75netfs K87portmap K89rdisc K99lvm2-monitor K02avahi-dnsconfd K10tcsd K50netconsole K85mdmonitor K87restorecond K90bluetooth K99microcode_ctl K02NetworkManager K10xfs K60crond K85mdmpd K88auditd K90network K99readahead_early K02oddjobd K15gpm K69rpcsvcgssd K85messagebus K88pcscd K91capi K99readahead_later K03yum-updatesd K15httpd K72autofs K85rpcgssd K88syslog K91isdn S00killall K05anacron K20nfs K73ypbind K85rpcidmapd K88wpa_supplicant K92ip6tables S01reboot K05atd K24irda K74acpid K86nfslock K89dund K92iptables K05conman K25sshd K74apmd K87irqbalance K89hidd K95firstboot
1.3 runlevel 查看当前运行级别
[root@test6 ~]# runlevel N 3 //前面的参数N是我之前运行级别，后边的3是我当前的运行级别
1.4 init 5 切换当前运行级别
1.5 不管在哪个级别运行，都是有7个控制台，f1-f7，f7是有桌面的控制台，f1-f6是命令行方式。当我们运行在级别3的时候，使用命令startx可以打开桌面方式。但当我们运行在5级别，用alt+f2，或者任意一个命令控制台时，运行startx发现报错，因为这个时候，桌面控制台已经运行在f7了。