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30.2.4. /sbin/init 程​​​​​​​序​​​​​​​

/sbin/init 程​​​​​​​序​​​​​​​(也​​​​​​​称​​​​​​​作​​​​​​​ init)协​​​​​​​调​​​​​​​余​​​​​​​下​​​​​​​的​​​​​​​引​​​​​​​导​​​​​​​过​​​​​​​程​​​​​​​并​​​​​​​为​​​​​​​用​​​​​​​户​​​​​​​配​​​​​​​置​​​​​​​环​​​​​​​境​​​​​​​。​​​​​​​
当​​​​​​​ init 命​​​​​​​令​​​​​​​启​​​​​​​动​​​​​​​时​​​​​​​,它​​​​​​​成​​​​​​​为​​​​​​​系​​​​​​​统​​​​​​​里​​​​​​​所​​​​​​​有​​​​​​​自​​​​​​​动​​​​​​​启​​​​​​​动​​​​​​​的​​​​​​​进​​​​​​​程​​​​​​​的​​​​​​​父​​​​​​​进​​​​​​​程​​​​​​​或​​​​​​​者​​​​​​​祖​​​​​​​父​​​​​​​(grandparent)进​​​​​​​程​​​​​​​。​​​​​​​首​​​​​​​先​​​​​​​,它​​​​​​​运​​​​​​​行​​​​​​​ /etc/rc.d/rc.sysinit 脚​​​​​​​本​​​​​​​,这​​​​​​​会​​​​​​​设​​​​​​​置​​​​​​​环​​​​​​​境​​​​​​​路​​​​​​​径​​​​​​​、​​​​​​​启​​​​​​​动​​​​​​​交​​​​​​​换​​​​​​​空​​​​​​​间​​​​​​​、​​​​​​​检​​​​​​​查​​​​​​​文​​​​​​​件​​​​​​​系​​​​​​​统​​​​​​​并​​​​​​​执​​​​​​​行​​​​​​​所​​​​​​​有​​​​​​​系​​​​​​​统​​​​​​​初​​​​​​​始​​​​​​​化​​​​​​​所​​​​​​​需​​​​​​​的​​​​​​​其​​​​​​​他​​​​​​​步​​​​​​​骤​​​​​​​。​​​​​​​例​​​​​​​如​​​​​​​,多​​​​​​​数​​​​​​​系​​​​​​​统​​​​​​​会​​​​​​​使​​​​​​​用​​​​​​​时​​​​​​​钟​​​​​​​,rc.sysinit 读​​​​​​​入​​​​​​​ /etc/sysconfig/clock 配​​​​​​​置​​​​​​​文​​​​​​​件​​​​​​​来​​​​​​​初​​​​​​​始​​​​​​​化​​​​​​​硬​​​​​​​件​​​​​​​时​​​​​​​钟​​​​​​​。​​​​​​​另​​​​​​​外​​​​​​​一​​​​​​​个​​​​​​​例​​​​​​​子​​​​​​​是​​​​​​​,如​​​​​​​果​​​​​​​有​​​​​​​必​​​​​​​须​​​​​​​初​​​​​​​始​​​​​​​化​​​​​​​的​​​​​​​特​​​​​​​殊​​​​​​​串​​​​​​​口​​​​​​​进​​​​​​​程​​​​​​​,rc.sysinit 会​​​​​​​执​​​​​​​行​​​​​​​ /etc/rc.serial 脚​​​​​​​本​​​​​​​。​​​​​​​
The init command then runs the /etc/inittab script, which describes how the system should be set up in each SysV init runlevel. Runlevels are a state, or mode, defined by the services listed in the SysV /etc/rc.d/rc<x>.d/ directory, where <x> is the number of the runlevel. For more information on SysV init runlevels, refer to 第 30.4 节 “SysV Init 运​​​​​​​行​​​​​​​级​​​​​​​别​​​​​​​”.
接​​​​​​​着​​​​​​​,init 命​​​​​​​令​​​​​​​为​​​​​​​系​​​​​​​统​​​​​​​设​​​​​​​置​​​​​​​ source function library,/etc/rc.d/init.d/functions,配​​​​​​​置​​​​​​​怎​​​​​​​样​​​​​​​启​​​​​​​动​​​​​​​、​​​​​​​杀​​​​​​​死​​​​​​​和​​​​​​​决​​​​​​​定​​​​​​​程​​​​​​​序​​​​​​​的​​​​​​​进​​​​​​​程​​​​​​​号​​​​​​​(PID)。​​​​​​​
init 程​​​​​​​序​​​​​​​根​​​​​​​据​​​​​​​ /etc/inittab 里​​​​​​​指​​​​​​​定​​​​​​​的​​​​​​​缺​​​​​​​省​​​​​​​运​​​​​​​行​​​​​​​级​​​​​​​别​​​​​​​遍​​​​​​​历​​​​​​​合​​​​​​​适​​​​​​​的​​​​​​​ rc 目​​​​​​​录​​​​​​​,启​​​​​​​动​​​​​​​所​​​​​​​有​​​​​​​的​​​​​​​后​​​​​​​台​​​​​​​进​​​​​​​程​​​​​​​。​​​​​​​不​​​​​​​同​​​​​​​的​​​​​​​运​​​​​​​行​​​​​​​级​​​​​​​别​​​​​​​对​​​​​​​应​​​​​​​不​​​​​​​同​​​​​​​的​​​​​​​rc 目​​​​​​​录​​​​​​​。​​​​​​​例​​​​​​​如​​​​​​​,/etc/rc.d/rc5.d/ 是​​​​​​​对​​​​​​​应​​​​​​​运​​​​​​​行​​​​​​​级​​​​​​​别​​​​​​​ 5 的​​​​​​​目​​​​​​​录​​​​​​​。​​​​​​​
当​​​​​​​引​​​​​​​导​​​​​​​至​​​​​​​运​​​​​​​行​​​​​​​级​​​​​​​别​​​​​​​ 5 时​​​​​​​,init 程​​​​​​​序​​​​​​​会​​​​​​​遍​​​​​​​历​​​​​​​ /etc/rc.d/rc5.d/ 来​​​​​​​决​​​​​​​定​​​​​​​启​​​​​​​动​​​​​​​和​​​​​​​停​​​​​​​止​​​​​​​哪​​​​​​​些​​​​​​​进​​​​​​​程​​​​​​​。​​​​​​​
下​​​​​​​面​​​​​​​是​​​​​​​ /etc/rc.d/rc5.d/ 目​​​​​​​录​​​​​​​内​​​​​​​容​​​​​​​的​​​​​​​示​​​​​​​例​​​​​​​:
K05innd -> ../init.d/innd 
K05saslauthd -> ../init.d/saslauthd 
K10dc_server -> ../init.d/dc_server 
K10psacct -> ../init.d/psacct 
K10radiusd -> ../init.d/radiusd 
K12dc_client -> ../init.d/dc_client 
K12FreeWnn -> ../init.d/FreeWnn 
K12mailman -> ../init.d/mailman 
K12mysqld -> ../init.d/mysqld 
K15httpd -> ../init.d/httpd 
K20netdump-server -> ../init.d/netdump-server 
K20rstatd -> ../init.d/rstatd 
K20rusersd -> ../init.d/rusersd 
K20rwhod -> ../init.d/rwhod 
K24irda -> ../init.d/irda 
K25squid -> ../init.d/squid 
K28amd -> ../init.d/amd 
K30spamassassin -> ../init.d/spamassassin 
K34dhcrelay -> ../init.d/dhcrelay 
K34yppasswdd -> ../init.d/yppasswdd 
K35dhcpd -> ../init.d/dhcpd 
K35smb -> ../init.d/smb 
K35vncserver -> ../init.d/vncserver 
K36lisa -> ../init.d/lisa 
K45arpwatch -> ../init.d/arpwatch 
K45named -> ../init.d/named 
K46radvd -> ../init.d/radvd 
K50netdump -> ../init.d/netdump 
K50snmpd -> ../init.d/snmpd 
K50snmptrapd -> ../init.d/snmptrapd 
K50tux -> ../init.d/tux 
K50vsftpd -> ../init.d/vsftpd 
K54dovecot -> ../init.d/dovecot 
K61ldap -> ../init.d/ldap 
K65kadmin -> ../init.d/kadmin 
K65kprop -> ../init.d/kprop 
K65krb524 -> ../init.d/krb524 
K65krb5kdc -> ../init.d/krb5kdc 
K70aep1000 -> ../init.d/aep1000 
K70bcm5820 -> ../init.d/bcm5820 
K74ypserv -> ../init.d/ypserv 
K74ypxfrd -> ../init.d/ypxfrd 
K85mdmpd -> ../init.d/mdmpd 
K89netplugd -> ../init.d/netplugd 
K99microcode_ctl -> ../init.d/microcode_ctl 
S04readahead_early -> ../init.d/readahead_early 
S05kudzu -> ../init.d/kudzu 
S06cpuspeed -> ../init.d/cpuspeed 
S08ip6tables -> ../init.d/ip6tables 
S08iptables -> ../init.d/iptables 
S09isdn -> ../init.d/isdn 
S10network -> ../init.d/network 
S12syslog -> ../init.d/syslog 
S13irqbalance -> ../init.d/irqbalance 
S13portmap -> ../init.d/portmap 
S15mdmonitor -> ../init.d/mdmonitor 
S15zebra -> ../init.d/zebra 
S16bgpd -> ../init.d/bgpd 
S16ospf6d -> ../init.d/ospf6d 
S16ospfd -> ../init.d/ospfd 
S16ripd -> ../init.d/ripd 
S16ripngd -> ../init.d/ripngd 
S20random -> ../init.d/random 
S24pcmcia -> ../init.d/pcmcia 
S25netfs -> ../init.d/netfs 
S26apmd -> ../init.d/apmd 
S27ypbind -> ../init.d/ypbind 
S28autofs -> ../init.d/autofs 
S40smartd -> ../init.d/smartd 
S44acpid -> ../init.d/acpid 
S54hpoj -> ../init.d/hpoj 
S55cups -> ../init.d/cups 
S55sshd -> ../init.d/sshd 
S56rawdevices -> ../init.d/rawdevices 
S56xinetd -> ../init.d/xinetd 
S58ntpd -> ../init.d/ntpd 
S75postgresql -> ../init.d/postgresql 
S80sendmail -> ../init.d/sendmail 
S85gpm -> ../init.d/gpm 
S87iiim -> ../init.d/iiim 
S90canna -> ../init.d/canna 
S90crond -> ../init.d/crond 
S90xfs -> ../init.d/xfs 
S95atd -> ../init.d/atd 
S96readahead -> ../init.d/readahead 
S97messagebus -> ../init.d/messagebus 
S97rhnsd -> ../init.d/rhnsd 
S99local -> ../rc.local
如​​​​​​​这​​​​​​​个​​​​​​​列​​​​​​​表​​​​​​​所​​​​​​​示​​​​​​​,所​​​​​​​有​​​​​​​真​​​​​​​正​​​​​​​启​​​​​​​动​​​​​​​和​​​​​​​停​​​​​​​止​​​​​​​服​​​​​​​务​​​​​​​的​​​​​​​脚​​​​​​​本​​​​​​​都​​​​​​​不​​​​​​​在​​​​​​​ /etc/rc.d/rc5.d/ 目​​​​​​​录​​​​​​​里​​​​​​​。​​​​​​​相​​​​​​​反​​​​​​​,/etc/rc.d/rc5.d/ 里​​​​​​​所​​​​​​​有​​​​​​​文​​​​​​​件​​​​​​​都​​​​​​​是​​​​​​​指​​​​​​​向​​​​​​​ /etc/rc.d/init.d/ 里​​​​​​​的​​​​​​​脚​​​​​​​本​​​​​​​的​​​​​​​符​​​​​​​号​​​​​​​链​​​​​​​接​​​​​​​。​​​​​​​在​​​​​​​ rc 里​​​​​​​使​​​​​​​用​​​​​​​符​​​​​​​号​​​​​​​链​​​​​​​接​​​​​​​,通​​​​​​​过​​​​​​​创​​​​​​​建​​​​​​​、​​​​​​​修​​​​​​​改​​​​​​​和​​​​​​​删​​​​​​​除​​​​​​​这​​​​​​​些​​​​​​​链​​​​​​​接​​​​​​​,就​​​​​​​可​​​​​​​以​​​​​​​对​​​​​​​不​​​​​​​同​​​​​​​的​​​​​​​运​​​​​​​行​​​​​​​级​​​​​​​别​​​​​​​进​​​​​​​行​​​​​​​重​​​​​​​新​​​​​​​配​​​​​​​置​​​​​​​,而​​​​​​​不​​​​​​​需​​​​​​​要​​​​​​​影​​​​​​​响​​​​​​​它​​​​​​​们​​​​​​​所​​​​​​​引​​​​​​​用​​​​​​​的​​​​​​​真​​​​​​​正​​​​​​​的​​​​​​​脚​​​​​​​本​​​​​​​。​​​​​​​
每​​​​​​​个​​​​​​​符​​​​​​​号​​​​​​​链​​​​​​​接​​​​​​​的​​​​​​​名​​​​​​​字​​​​​​​都​​​​​​​以​​​​​​​ K 或​​​​​​​者​​​​​​​ S 开​​​​​​​头​​​​​​​。​​​​​​​以​​​​​​​ K 开​​​​​​​头​​​​​​​的​​​​​​​链​​​​​​​接​​​​​​​是​​​​​​​在​​​​​​​这​​​​​​​个​​​​​​​运​​​​​​​行​​​​​​​级​​​​​​​别​​​​​​​需​​​​​​​要​​​​​​​杀​​​​​​​死​​​​​​​的​​​​​​​进​​​​​​​程​​​​​​​,而​​​​​​​以​​​​​​​ S 开​​​​​​​头​​​​​​​的​​​​​​​链​​​​​​​接​​​​​​​是​​​​​​​需​​​​​​​要​​​​​​​启​​​​​​​动​​​​​​​的​​​​​​​进​​​​​​​程​​​​​​​。​​​​​​​
The init command first stops all of the K symbolic links in the directory by issuing the /etc/rc.d/init.d/<command> stop command, where <command> is the process to be killed. It then starts all of the S symbolic links by issuing /etc/rc.d/init.d/<command> start.

注意

在​​​​​​​系​​​​​​​统​​​​​​​完​​​​​​​成​​​​​​​引​​​​​​​导​​​​​​​后​​​​​​​,你​​​​​​​也​​​​​​​可​​​​​​​以​​​​​​​ root 登​​​​​​​录​​​​​​​并​​​​​​​执​​​​​​​行​​​​​​​这​​​​​​​些​​​​​​​脚​​​​​​​本​​​​​​​来​​​​​​​启​​​​​​​动​​​​​​​和​​​​​​​停​​​​​​​止​​​​​​​服​​​​​​​务​​​​​​​。​​​​​​​例​​​​​​​如​​​​​​​,/etc/rc.d/init.d/httpd stop 可​​​​​​​用​​​​​​​来​​​​​​​停​​​​​​​止​​​​​​​ Apache HTTP 服​​​​​​​务​​​​​​​器​​​​​​​。​​​​​​​
每​​​​​​​个​​​​​​​符​​​​​​​号​​​​​​​链​​​​​​​接​​​​​​​都​​​​​​​用​​​​​​​数​​​​​​​字​​​​​​​结​​​​​​​尾​​​​​​​来​​​​​​​指​​​​​​​明​​​​​​​开​​​​​​​始​​​​​​​的​​​​​​​顺​​​​​​​序​​​​​​​。​​​​​​​可​​​​​​​以​​​​​​​修​​​​​​​改​​​​​​​这​​​​​​​个​​​​​​​数​​​​​​​字​​​​​​​来​​​​​​​决​​​​​​​定​​​​​​​服​​​​​​​务​​​​​​​启​​​​​​​动​​​​​​​或​​​​​​​停​​​​​​​止​​​​​​​的​​​​​​​顺​​​​​​​序​​​​​​​。​​​​​​​数​​​​​​​字​​​​​​​越​​​​​​​小​​​​​​​,就​​​​​​​越​​​​​​​早​​​​​​​开​​​​​​​始​​​​​​​运​​​​​​​行​​​​​​​。​​​​​​​有​​​​​​​着​​​​​​​相​​​​​​​同​​​​​​​数​​​​​​​字​​​​​​​的​​​​​​​符​​​​​​​号​​​​​​​链​​​​​​​接​​​​​​​则​​​​​​​按​​​​​​​字​​​​​​​母​​​​​​​顺​​​​​​​序​​​​​​​来​​​​​​​运​​​​​​​行​​​​​​​。​​​​​​​

注意

One of the last things the init program executes is the /etc/rc.d/rc.local file. This file is useful for system customization. Refer to 第 30.3 节 “在​​​​​​​引​​​​​​​导​​​​​​​时​​​​​​​运​​​​​​​行​​​​​​​其​​​​​​​他​​​​​​​的​​​​​​​程​​​​​​​序​​​​​​​” for more information about using the rc.local file.
After the init command has progressed through the appropriate rc directory for the runlevel, the /etc/inittab script forks an /sbin/mingetty process for each virtual console (login prompt) allocated to the runlevel. Runlevels 2 through 5 have all six virtual consoles, while runlevel 1 (single user mode) has one, and runlevels 0 and 6 have none. The /sbin/mingetty process opens communication pathways to tty devices[14], sets their modes, prints the login prompt, accepts the user's username and password, and initiates the login process.
在​​​​​​​运​​​​​​​行​​​​​​​级​​​​​​​别​​​​​​​ 5 下​​​​​​​,/etc/inittab 会​​​​​​​运​​​​​​​行​​​​​​​一​​​​​​​个​​​​​​​叫​​​​​​​ /etc/X11/prefdm 的​​​​​​​脚​​​​​​​本​​​​​​​。​​​​​​​这​​​​​​​个​​​​​​​ prefdm 脚​​​​​​​本​​​​​​​执​​​​​​​行​​​​​​​首​​​​​​​选​​​​​​​的​​​​​​​ X 显​​​​​​​示​​​​​​​管​​​​​​​理​​​​​​​器​​​​​​​[15]gdm、​​​​​​​kdm 或​​​​​​​ xdm,依​​​​​​​ /etc/sysconfig/desktop 里​​​​​​​的​​​​​​​设​​​​​​​置​​​​​​​而​​​​​​​定​​​​​​​。​​​​​​​
运​​​​​​​行​​​​​​​完​​​​​​​毕​​​​​​​后​​​​​​​,系​​​​​​​统​​​​​​​将​​​​​​​在​​​​​​​运​​​​​​​行​​​​​​​级​​​​​​​别​​​​​​​ 5 下​​​​​​​操​​​​​​​作​​​​​​​并​​​​​​​显​​​​​​​示​​​​​​​一​​​​​​​个​​​​​​​登​​​​​​​录​​​​​​​屏​​​​​​​幕​​​​​​​。​​​​​​​


[14] Refer to the Red Hat Enterprise Linux Deployment Guide for more information about tty devices.
[15] 请​​​​​​​参​​​​​​​考​​​​​​​《​​​​​​​Red Hat Enterprise Linux 部​​​​​​​署​​​​​​​指​​​​​​​南​​​​​​​》​​​​​​​里​​​​​​​关​​​​​​​于​​​​​​​显​​​​​​​示​​​​​​​管​​​​​​​理​​​​​​​器​​​​​​​的​​​​​​​更​​​​​​​多​​​​​​​信​​​​​​​息​​​​​​​。​​​​​​​