首页 > 代码库 > [转] 浅谈Linux系统的启动流程

[转] 浅谈Linux系统的启动流程

原文:http://blog.csdn.net/justdb/article/details/9621271 版权声明:本文为博主原创文章。

 

 

Linux系统的启动时通过读取不同的配置文件,执行相应的Shell脚本完成的。当然本文只是简单的从文件的角度分析,更深层次的本文没涉及。    

主要读取了以下文件:

 1 /boot/grub/grub.conf 2 /etc/inittab 3 /etc/rc5.d(rc.d) 0-99 Seq 4 /etc/passwd (Login,input username and password) 5 /etc/shadow 6 /etc/profile:init the env var of user 7 /etc/profile.d/*.sh 8 ~/.bash_profile 9 ~/.bash_history10 ~/.bashrc11 /etc/bashrc

我们首先来看grub.conf文件

 1 [root@larrywen grub]# ll menu.lst    2 lrwxrwxrwx. 1 root root 11  7o?=o?= 19 10:52 menu.lst -> ./grub.conf   3 [root@larrywen grub]# pwd   4 /boot/grub   5 grub.conf文件内容:   6 default=0   7 timeout=5   8 splashimage=(hd0,0)/boot/grub/splash.xpm.gz   9 hiddenmenu  10 title Red Hat Enterprise Linux (2.6.32-220.el6.i686)  11          root (hd0,0)  12          kernel /boot/vmlinuz-2.6.32-220.el6.i686 ro  13 root=UUID=ed98469d-857b-4ae5-91e4-118e0167ead7 rd_NO_LUKS rd_NO_LVM  14 LANG=en_US.UTF-8 rd_NO_MD quiet SYSFONT=lat    arcyrheb-sun16 rhgb  15 crashkernel=auto  KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM  16          initrd /boot/initramfs-2.6.32-220.el6.i686.img  

执行runlevel命令可以看到启动级别是5

1 [root@larrywen grub]# runlevel  2 N 5

我们进入etc目录,可以看到很多rcX.d目录

1 [root@larrywen grub]# cd /etc/init.d  2   3 [root@larrywen init.d]# cd /etc  4 [root@larrywen etc]# cd rc  5 rc          rc0.d/      rc1.d/      rc2.d/      rc3.d/      rc4.d/      rc5.d/  6 rc6.d/      rc.d/       rc.local    rc.sysinit    

我们进入/etc/profile.d目录,可以看到很多可执行脚本

 1 [root@localhost test]# ll /etc/profile.d/*.sh   2 -rw-r--r--. 1 root root 1143 Apr 28  2010 /etc/profile.d/colorls.sh   3 -rw-r--r--. 1 root root   78 Apr 21  2010 /etc/profile.d/cvs.sh   4 -rw-r--r--. 1 root root  192 Dec 12  2005 /etc/profile.d/glib2.sh   5 -rw-r--r--. 1 root root   70 Aug 12  2010 /etc/profile.d/gnome-ssh-askpass.sh   6 -rwxr-xr-x. 1 root root  288 Sep 24  2009 /etc/profile.d/kde.sh   7 -rw-r--r--. 1 root root 2706 Sep  2  2010 /etc/profile.d/lang.sh   8 -rw-r--r--. 1 root root  108 Feb  7  2007 /etc/profile.d/less.sh   9 -rw-r--r--. 1 root root  933 Jun 30  2010 /etc/profile.d/qt.sh  10 -rw-r--r--. 1 root root 2142 Sep  8  2010 /etc/profile.d/udisks-bash-completion.sh  11 -rw-r--r--. 1 root root  269 May 19  2010 /etc/profile.d/vim.sh  12 -rw-r--r--. 1 root root  169 May 20  2009 /etc/profile.d/which2.sh  

 因为启动级别是5,所以我们进入rc5.d,可以看到很多文件,S表示当系统启动时执行,K表示当系统关闭时执行。

[root@localhost grub]# ll /etc/rc5.d/  K01certmonger       K50netconsole       K75ntpdate          K89rdisc            S11auditd           S24avahi-daemon     S26pcscd            S82abrtd  K01smartd           K50snmpd            K76ipsec            K95cgconfig         S11portreserve      S24nfslock          S26udev-post        S85qpidd  K02oddjobd          K50snmptrapd        K80kdump            K95firstboot        S12rsyslog          S24openct           S28autofs           S90crond  K10psacct           K50vsftpd           K80sblim-sfcb       S00microcode_ctl    S13cpuspeed         S24rpcgssd          S30vboxadd          S95atd  K10saslauthd        K60nfs              K80sssd             S01sysstat          S13irqbalance       S24rpcidmapd        S30vboxadd-x11      S97rhnsd  K15httpd            K69rpcsvcgssd       K84wpa_supplicant   S02lvm2-monitor     S13rpcbind          S25cups             S35vboxadd-service  S98tog-pegasus  K20tomcat6          K73ypbind           K86cgred            S08ip6tables        S15mdmonitor        S25netfs            S50bluetooth        S99local  K36mysqld           K74nscd             K87restorecond      S08iptables         S22messagebus       S26acpid            S55sshd               K50dnsmasq          K74ntpd             K88nslcd            S10network          S23NetworkManager   S26haldaemon        S80postfix      

我们再来看看用户主目录下的.bashrc文件内容

 1 [root@localhost grub]# cat ~/.bashrc    2 # .bashrc   3    4 # User specific aliases and functions   5    6 alias rm=rm -i   7 alias cp=cp -i   8 alias mv=mv -i   9   10 # Source global definitions  11 if [ -f /etc/bashrc ]; then  12     . /etc/bashrc  13 fi  

我们再来看看用户主目录下的.bash_profile文件内容

 1 [root@localhost grub]# cat ~/.bash_profile    2 # .bash_profile   3    4 # Get the aliases and functions   5 if [ -f ~/.bashrc ]; then   6     . ~/.bashrc   7 fi   8    9 # User specific environment and startup programs  10   11 PATH=$PATH:$HOME/bin  12   13 export PATH  

完整的流程图如下图:

技术分享

 

[转] 浅谈Linux系统的启动流程