linux 系统服务详解

清单 1. 运行级5的指向服务程序的链接 # cd /etc/rc.d/rc5.d # ls -al total 8 drwxr-xr-x 2 root root 4096 Jul 15 09:29 . drwxr-xr-x 10 root root 4096 Jun 21 08:52 .. lrwxrwxrwx 1 root root 19 Jan 1 2000 K05saslauthd -> ../init.d/saslauthd lrwxrwxrwx 1 root root 20 Feb 1 2003 K15postgresql -> ../init.d/postgresql lrwxrwxrwx 1 root root 13 Jan 1 2000 K20nfs -> ../init.d/nfs lrwxrwxrwx 1 root root 14 Jan 1 2000 K24irda -> ../init.d/irda lrwxrwxrwx 1 root root 17 Jan 1 2000 K35winbind -> ../init.d/winbind lrwxrwxrwx 1 root root 15 Jan 1 2000 K50snmpd -> ../init.d/snmpd lrwxrwxrwx 1 root root 19 Jan 1 2000 K50snmptrapd -> ../init.d/snmptrapd lrwxrwxrwx 1 root root 16 Jun 21 09:43 K50vsftpd -> ../init.d/vsftpd lrwxrwxrwx 1 root root 16 Jun 21 08:57 K73ypbind -> ../init.d/ypbind lrwxrwxrwx 1 root root 14 Jun 21 08:54 K74nscd -> ../init.d/nscd lrwxrwxrwx 1 root root 18 Feb 8 11:15 K92iptables -> ../init.d/iptables lrwxrwxrwx 1 root root 19 Feb 1 2003 K95firstboot -> ../init.d/firstboot lrwxrwxrwx 1 root root 15 Jan 1 2000 S05kudzu -> ../init.d/kudzu lrwxrwxrwx 1 root root 14 Jun 21 08:55 S09isdn -> ../init.d/isdn lrwxrwxrwx 1 root root 17 Jan 1 2000 S10network -> ../init.d/network lrwxrwxrwx 1 root root 16 Jan 1 2000 S12syslog -> ../init.d/syslog lrwxrwxrwx 1 root root 17 Jan 1 2000 S13portmap -> ../init.d/portmap lrwxrwxrwx 1 root root 17 Jan 1 2000 S14nfslock -> ../init.d/nfslock lrwxrwxrwx 1 root root 18 Jan 1 2000 S17keytable -> ../init.d/keytable lrwxrwxrwx 1 root root 16 Jan 1 2000 S20random -> ../init.d/random lrwxrwxrwx 1 root root 16 Jun 21 08:52 S24pcmcia -> ../init.d/pcmcia lrwxrwxrwx 1 root root 15 Jan 1 2000 S25netfs -> ../init.d/netfs lrwxrwxrwx 1 root root 14 Jan 1 2000 S26apmd -> ../init.d/apmd lrwxrwxrwx 1 root root 16 Jan 1 2000 S28autofs -> ../init.d/autofs lrwxrwxrwx 1 root root 14 Jan 1 2000 S55sshd -> ../init.d/sshd lrwxrwxrwx 1 root root 20 Jan 1 2000 S56rawdevices -> ../init.d/rawdevices lrwxrwxrwx 1 root root 16 Jan 1 2000 S56xinetd -> ../init.d/xinetd lrwxrwxrwx 1 root root 14 Feb 1 2003 S58ntpd -> ../init.d/ntpd lrwxrwxrwx 1 root root 13 Jun 21 10:42 S60afs -> ../init.d/afs lrwxrwxrwx 1 root root 13 Jan 1 2000 S60lpd -> ../init.d/lpd lrwxrwxrwx 1 root root 16 Feb 8 17:26 S78mysqld -> ../init.d/mysqld lrwxrwxrwx 1 root root 18 Jan 1 2000 S80sendmail -> ../init.d/sendmail lrwxrwxrwx 1 root root 13 Jan 1 2000 S85gpm -> ../init.d/gpm lrwxrwxrwx 1 root root 15 Mar 22 08:24 S85httpd -> ../init.d/httpd lrwxrwxrwx 1 root root 15 Jan 1 2000 S90crond -> ../init.d/crond lrwxrwxrwx 1 root root 13 Jan 1 2000 S90xfs -> ../init.d/xfs lrwxrwxrwx 1 root root 17 Jan 1 2000 S95anacron -> ../init.d/anacron lrwxrwxrwx 1 root root 13 Jan 1 2000 S95atd -> ../init.d/atd lrwxrwxrwx 1 root root 15 Jun 21 08:57 S97rhnsd -> ../init.d/rhnsd lrwxrwxrwx 1 root root 14 Jul 15 09:29 S98wine -> ../init.d/wine lrwxrwxrwx 1 root root 13 Feb 8 17:26 S99db2 -> ../init.d/db2 lrwxrwxrwx 1 root root 11 Jun 21 08:52 S99local -> ../rc.local #

这看起来好象是非常复杂的系统，但实际上它提供了极好的灵活性，因为如果您想临时禁止某个特定运行级中的服务，只要把适当的符号链接删除即可。不过，手工管理这些链接可能会让人感觉厌烦，并且容易出错（尤其当您累了的时候），所以可以采用一个相对好一些的方法，使用 chkconfig 命令。

如何找出激活的服务

想查看您已经激活了多少服务，运行这个命令： /sbin/chkconfig --list

清单 2列出了这个命令的输出。您可以看到，每一行

有八列。

chkconfig 命令还可以用来切换任何一个服务的开或关。详细信息请参考手册页（man chkconfig）。

如果您有一个新版本的 chkconfig ，您会在主输出的最后一部分看到有关 xinetd (Internet services daemon)的配置。为了减化说明，此部分没有列入清单2中。

清单 2. chkconfig --list|sort的输出 afs 0:off 1:off 2:off 3:on 4:off 5:on 6:off anacron 0:off 1:off 2:on 3:on 4:on 5:on 6:off apmd 0:off 1:off 2:on 3:on 4:on 5:on 6:off atd 0:off 1:off 2:off 3:on 4:on 5:on 6:off autofs 0:off 1:off 2:off 3:on 4:on 5:on 6:off crond 0:off 1:off 2:on 3:on 4:on 5:on 6:off db2 0:off 1:off 2:off 3:on 4:off 5:on 6:off firstboot 0:off 1:off 2:off 3:off 4:off 5:off 6:off gpm 0:off 1:off 2:on 3:on 4:on 5:on 6:off httpd 0:off 1:off 2:off 3:off 4:off 5:on 6:off iptables 0:off 1:off 2:off 3:off 4:off 5:off 6:off irda 0:off 1:off 2:off 3:off 4:off 5:off 6:off isdn 0:off 1:off 2:on 3:on 4:on 5:on 6:off keytable 0:off 1:on 2:on 3:on 4:on 5:on 6:off kudzu 0:off 1:off 2:off 3:on 4:on 5:on 6:off lpd 0:off 1:off 2:on 3:on 4:on 5:on 6:off mysqld 0:off 1:off 2:off 3:on 4:off 5:on 6:off netfs 0:off 1:off 2:off 3:on 4:on 5:on 6:off network 0:off 1:off 2:on 3:on 4:on 5:on 6:off nfs 0:off 1:off 2:off 3:off 4:off 5:off 6:off nfslock 0:off 1:off 2:off 3:on 4:on 5:on 6:off nscd 0:off 1:off 2:off 3:off 4:off 5:off 6:off ntpd 0:off 1:off 2:off 3:on 4:off 5:on 6:off pcmcia 0:off 1:off 2:on 3:on 4:on 5:on 6:off portmap 0:off 1:off 2:off 3:on 4:on 5:on 6:off postgresql 0:off 1:off 2:off 3:off 4:off 5:off 6:off random 0:off 1:off 2:on 3:on 4:on 5:on 6:off rawdevices 0:off 1:off 2:off 3:on 4:on 5:on 6:off rhnsd 0:off 1:off 2:off 3:on 4:on 5:on 6:off saslauthd 0:off 1:off 2:off 3:off 4:off 5:off 6:off