Linux系统服务基础
Linux系统服务基础
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本篇随笔将主要讲解Linux系统的服务基础，从本篇随笔开始，后续的Linux系列随笔将主要记录常用的各种服务的配置，包括DNS、WWW、Mail等等各种服务的配置。。。
一、系统服务的基本概念
服务，其实就是运行在操作系统后台的一个或者多个应用程序，为计算机系统或用户提供某项特定的服务。
在我们的windows操作系统中，其在后台也运行了许许多多的服务。例如我们装的杀毒软件，其在后台运行了许多我们看不见的服务程序，通过这些服务来为用户或者计算机系统来提高特定的功能。
服务通常是不中断运行的，随时准备接受请求，从而提供某项服务。例如我们日常使用的网页服务，其就是由一个运行在所访问网站的服务器上的httpd服务提供的服务，我们通过在浏览器输入需要访问网站的域名，服务器端的httpd服务就会随时的接收我们发送过来的请求，并响应回给我们的用户。
我们Linux系统绝大多数服务都是网络服务，例如邮件服务、FTP服务、httpd服务等等，网络服务可以使为其他用户、其他计算机提供特定的服务。
二、System V
上面粗略的讲解了一些系统服务的概念，自己感觉写的一般，总的来说，Linux系统通常作为服务器端的操作系统来用的，所以Linux系统提供了许许多的的服务，有些服务需要我们自己来进行配置，这些服务的目的就是为了给我们的计算机、用户提供某项特定的功能。那么对于各种不同的服务，Linux系统是怎么样来统一进行管理的呢？
在Linux操作系统中，Linux对于服务的管理体系是沿用了System V的服务管理体系，System V原来是早期AT&T的一个操作系统。
对于Linux系统，System V提供了运行级别的概念，还记得之前一直提到过的Linux的启动运行级别吗？没错，System V一共提供了7种运行级别
0 关机
1 单用户模式
2 不带网络的多用户模式
3 带网络的多用户模式，纯文本界面
4 未使用
5 带网络的多用户模式，图形界面
6 重启
对于我们来说，通常使用的是级别3和级别5，每个级别下都有对应的启动、不启动的服务，比如单用户模式下，所有的服务都是不启动，这些都是通过System V这个服务管理体系来决定的
System V定义了init为系统启动的第一个进程，进程PID=1，这个进程的目的就是去查看 /etc/inittab 中的系统启动级别从而来启动对应的服务
对于不同的服务，因为其提供该服务的厂家不同，所以这些的服务的启动、关闭机制通常不同，在Linux系统中，为了方便的管理这些服务，每个服务的启动、结束、重启等操作都由一个System V脚本来进行控制，拥有固定的格式。
对于Linux系统上的服务，这些服务的System V脚本文件都是存放在 /etc/rc.d/init.d 这个目录下
[root@xiaoluo ~]# cd /etc/rc.d/init.d/ [root@xiaoluo init.d]# ls abrt - ccpp firstboot messagebus quota_nld snmptrapd abrtd functions mysqld rdisc spice - vdagentd abrt - oops haldaemon netconsole restorecond sshd acpid halt netfs rngd sssd atd htcacheclean network rpcbind sysstat auditd httpd NetworkManager rpcgssd udev - post autofs ip6tables nfs rpcidmapd vboxadd blk -availability iptables nfslock rpcsvcgssd vboxadd- service bluetooth irqbalance ntpd rsyslog vboxadd - x11 certmonger kdump ntpdate sandbox vncserver cpuspeed killall oddjobd saslauthd wdaemon crond lvm2 - lvmetad portreserve single winbind cups lvm2 - monitor postfix smartd wpa_supplicant dnsmasq mdmonitor psacct snmpd ypbind
我们看到在这个目录下，存在了许多纯文本文件，这些文件都是系统每一个服务的System V的脚本文件，对于该脚本文件，我们要启动什么服务，都是通过这些脚本文件来启动的，我们也可以通过编写System V脚本文件来手工创建一个我们自己的由System V来控制的服务。
对于Linux的所有的这些服务，我们通过 service 这个命令来进行统一的管理
命令 service 可以调用指定服务的System V脚本，并执行指定的动作
service 服务名 [start | stop | restart | status]
例如我们这里需要启动 httpd 这个服务，可以使用 service httpd start 这个命令
[root@xiaoluo init.d]# service httpd start
Starting httpd: httpd: apr_sockaddr_info_get() failed for xiaoluo
httpd: Could not reliably determine the server ' s fully qualified domain name, using 127.0.0.1 for ServerName
[ OK ]
我们也可以通过 service httpd status 来查看当前服务的启动情况
[root@xiaoluo init.d]# service httpd status httpd (pid 6589 ) is running.
如果我们要重启该服务，或者关闭服务可以分别使用 service httpd restart 、service httpd stop命令
[root@xiaoluo init.d]# service httpd restart
Stopping httpd: [ OK ]
Starting httpd: httpd: apr_sockaddr_info_get() failed for xiaoluo
httpd: Could not reliably determine the server ' s fully qualified domain name, using 127.0.0.1 for ServerName
[ OK ]
[root@xiaoluo init.d]# service httpd stop
Stopping httpd: [ OK ]
对于Linux系统的这些服务，我们都是通过 service 这个命令去调用该服务对应的System V脚本，并执行其指定的动作
刚才我们也说到了，System V定义了运行级别的概念，每个运行级别对应有启动、不启动的服务，在 /etc/rc.d 这个目录下，除了我们刚才的 init.d 这个目录，我们还发现还有其它的一些目录，诸如 rc0.d、rc1.d等
[root@xiaoluo rc.d]# ll total 60 drwxr -xr-x. 2 root root 4096 May 27 22 : 57 init.d -rwxr-xr-x. 1 root root 2617 Feb 22 19 : 18 rc drwxr -xr-x. 2 root root 4096 Jun 1 14 : 32 rc0.d drwxr -xr-x. 2 root root 4096 Jun 1 14 : 32 rc1.d drwxr -xr-x. 2 root root 4096 Jun 1 14 : 32 rc2.d drwxr -xr-x. 2 root root 4096 Jun 1 14 : 32 rc3.d drwxr -xr-x. 2 root root 4096 Jun 1 14 : 32 rc4.d drwxr -xr-x. 2 root root 4096 Jun 1 14 : 32 rc5.d drwxr -xr-x. 2 root root 4096 Jun 1 14 : 32 rc6.d -rwxr-xr-x. 1 root root 220 Feb 22 19 : 18 rc.local -rwxr-xr-x. 1 root root 19472 Feb 22 19 : 18 rc.sysinit
这些 rc0.d ，rc3.d这些目录就分别对应了系统的7中启动级别，每个目录里面都存放了许多的文件，每个文件对应着一个特定的服务，并标志有是否开机启动以及启动顺序，例如我们进入到 rc5.d 这个目录
[root@xiaoluo rc.d]# cd rc5.d/ [root@xiaoluo rc5.d]# ls - l total 0 lrwxrwxrwx. 1 root root 16 May 14 01 : 26 K01smartd -> init.d/ smartd lrwxrwxrwx. 1 root root 17 May 14 01 : 21 K02oddjobd -> init.d/ oddjobd lrwxrwxrwx. 1 root root 17 May 14 01 : 28 K05wdaemon -> init.d/ wdaemon lrwxrwxrwx. 1 root root 16 May 14 01 : 26 K10psacct -> init.d/ psacct lrwxrwxrwx. 1 root root 19 May 14 01 : 21 K10saslauthd -> init.d/ saslauthd lrwxrwxrwx. 1 root root 22 May 14 01 : 21 K15htcacheclean -> init.d/ htcacheclean lrwxrwxrwx. 1 root root 15 Jun 1 14 : 32 K15httpd -> init.d/ httpd lrwxrwxrwx. 1 root root 19 May 27 22 : 57 K35vncserver -> init.d/ vncserver lrwxrwxrwx. 1 root root 17 May 14 01 : 21 K50dnsmasq -> init.d/ dnsmasq lrwxrwxrwx. 1 root root 20 May 14 01 : 19 K50netconsole -> init.d/ netconsole lrwxrwxrwx. 1 root root 15 May 14 01 : 21 K50snmpd -> init.d/ snmpd lrwxrwxrwx. 1 root root 19 May 14 01 : 21 K50snmptrapd -> init.d/ snmptrapd lrwxrwxrwx. 1 root root 13 May 14 01 : 19 K60nfs -> init.d/ nfs lrwxrwxrwx. 1 root root 20 May 14 01 : 19 K69rpcsvcgssd -> init.d/ rpcsvcgssd lrwxrwxrwx. 1 root root 17 May 14 01 : 30 K73winbind -> init.d/ winbind lrwxrwxrwx. 1 root root 14 May 14 01 : 35 K74ntpd -> init.d/ ntpd lrwxrwxrwx. 1 root root 17 May 14 01 : 21 K75ntpdate -> init.d/ ntpdate lrwxrwxrwx. 1 root root 19 May 14 01 : 26 K75quota_nld -> init.d/ quota_nld lrwxrwxrwx. 1 root root 16 May 14 01 : 30 K76ypbind -> init.d/ ypbind lrwxrwxrwx. 1 root root 15 May 14 01 : 35 K80kdump -> init.d/ kdump lrwxrwxrwx. 1 root root 24 Jun 1 14 : 32 K84wpa_supplicant -> init.d/ wpa_supplicant lrwxrwxrwx. 1 root root 21 May 14 01 : 19 K87restorecond -> init.d/ restorecond lrwxrwxrwx. 1 root root 14 Jun 1 14 : 32 K88sssd -> init.d/ sssd lrwxrwxrwx. 1 root root 15 May 14 01 : 19 K89rdisc -> init.d/ rdisc lrwxrwxrwx. 1 root root 19 May 14 01 : 35 K95firstboot -> init.d/ firstboot lrwxrwxrwx. 1 root root 14 May 14 01 : 26 K99rngd -> init.d/ rngd lrwxrwxrwx. 1 root root 17 May 14 01 : 24 S01sysstat -> init.d/ sysstat lrwxrwxrwx. 1 root root 22 May 14 01 : 25 S02lvm2-monitor -> init.d/lvm2- monitor lrwxrwxrwx. 1 root root 19 May 14 01 : 22 S08ip6tables -> init.d/ ip6tables lrwxrwxrwx. 1 root root 18 May 14 01 : 19 S08iptables -> init.d/ iptables lrwxrwxrwx. 1 root root 17 May 14 01 : 19 S10network -> init.d/ network lrwxrwxrwx. 1 root root 16 May 31 11 : 27 S11auditd -> init.d/ auditd lrwxrwxrwx. 1 root root 21 May 14 01 : 13 S11portreserve -> init.d/ portreserve lrwxrwxrwx. 1 root root 17 May 14 01 : 21 S12rsyslog -> init.d/ rsyslog lrwxrwxrwx. 1 root root 18 May 14 01 : 26 S13cpuspeed -> init.d/ cpuspeed lrwxrwxrwx. 1 root root 20 May 14 01 : 26 S13irqbalance -> init.d/ irqbalance lrwxrwxrwx. 1 root root 17 May 14 01 : 14 S13rpcbind -> init.d/ rpcbind lrwxrwxrwx. 1 root root 19 May 14 01 : 19 S15mdmonitor -> init.d/ mdmonitor lrwxrwxrwx. 1 root root 20 May 14 01 : 12 S22messagebus -> init.d/ messagebus lrwxrwxrwx. 1 root root 24 May 26 14 : 01 S23NetworkManager -> init.d/ NetworkManager lrwxrwxrwx. 1 root root 17 Jun 1 14 : 32 S24nfslock -> init.d/ nfslock lrwxrwxrwx. 1 root root 17 Jun 1 14 : 32 S24rpcgssd -> init.d/ rpcgssd lrwxrwxrwx. 1 root root 19 Jun 1 14 : 32 S24rpcidmapd -> init.d/ rpcidmapd lrwxrwxrwx. 1 root root 26 May 14 01 : 25 S25blk-availability -> init.d/blk- availability lrwxrwxrwx. 1 root root 14 May 14 01 : 19 S25cups -> init.d/ cups lrwxrwxrwx. 1 root root 15 May 14 01 : 19 S25netfs -> init.d/ netfs lrwxrwxrwx. 1 root root 15 May 14 01 : 26 S26acpid -> init.d/ acpid lrwxrwxrwx. 1 root root 19 May 14 01 : 20 S26haldaemon -> init.d/ haldaemon lrwxrwxrwx. 1 root root 19 May 14 01 : 19 S26udev-post -> init.d/udev- post lrwxrwxrwx. 1 root root 16 May 14 01 : 22 S28autofs -> init.d/ autofs lrwxrwxrwx. 1 root root 17 May 14 02 : 15 S30vboxadd -> init.d/ vboxadd lrwxrwxrwx. 1 root root 21 May 14 02 : 16 S30vboxadd-x11 -> init.d/vboxadd- x11 lrwxrwxrwx. 1 root root 25 May 14 02 : 16 S35vboxadd-service -> init.d/vboxadd- service lrwxrwxrwx. 1 root root 19 May 14 01 : 22 S50bluetooth -> init.d/ bluetooth lrwxrwxrwx. 1 root root 14 May 14 01 : 26 S55sshd -> init.d/ sshd lrwxrwxrwx. 1 root root 16 May 14 14 : 29 S64mysqld -> init.d/ mysqld lrwxrwxrwx. 1 root root 24 May 14 01 : 26 S70spice-vdagentd -> init.d/spice- vdagentd lrwxrwxrwx. 1 root root 17 May 14 01 : 21 S80postfix -> init.d/ postfix lrwxrwxrwx. 1 root root 19 May 14 01 : 16 S82abrt-ccpp -> init.d/abrt- ccpp lrwxrwxrwx. 1 root root 15 May 14 01 : 16 S82abrtd -> init.d/ abrtd lrwxrwxrwx. 1 root root 15 May 14 01 : 22 S90crond -> init.d/ crond lrwxrwxrwx. 1 root root 13 May 14 01 : 14 S95atd -> init.d/ atd lrwxrwxrwx. 1 root root 20 May 14 01 : 21 S99certmonger -> init.d/ certmonger lrwxrwxrwx. 1 root root 11 May 14 01 : 19 S99local -> rc.local
我们发现，在这些目录里面，存放的都是链接文件，不过这每一个链接文件的名字都有着严格的规定。每一个链接文件都由3部分组成
K15httpd -> init.d/httpd S55sshd -> init.d/sshd
①第一个部分是第一个字母K或者S，表示该服务是不是是不是开机自动启动，K表示开机不启动，S表示开机就启动
②第二个部分是一个数字，这个数字代表的是该服务的启动顺序，服务启动的顺序非常的重要，例如我们的网络服务需要在邮件服务之前启动
③第三个部分就是对应服务的名字，该链接文件其实都是指向的是 init.d 这个目录下的System V脚本文件
我们如果希望某服务开机就启动，可以通过修改 rc5.d 目录下的链接文件，不过这样做很麻烦，Linux系统提供了一个 chkconfig 命令可以来设置服务是否开机启动
例如我们通过 chkconfig --list 命令来查看所有服务的开机启动情况
[root@xiaoluo rc5.d]# chkconfig -- list NetworkManager 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off abrt -ccpp 0 :off 1 :off 2 :off 3 :on 4 :off 5 :on 6 :off abrtd 0 :off 1 :off 2 :off 3 :on 4 :off 5 :on 6 :off acpid 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 auditd 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off autofs 0 :off 1 :off 2 :off 3 :on 4 :on 5 :on 6 :off blk -availability 0 :off 1 :on 2 :on 3 :on 4 :on 5 :on 6 :off bluetooth 0 :off 1 :off 2 :off 3 :on 4 :on 5 :on 6 :off certmonger 0 :off 1 :off 2 :off 3 :on 4 :on 5 :on 6 :off cpuspeed 0 :off 1 :on 2 :on 3 :on 4 :on 5 :on 6 :off crond 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off cups 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off dnsmasq 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off firstboot 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off haldaemon 0 :off 1 :off 2 :off 3 :on 4 :on 5 :on 6 :off htcacheclean 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off httpd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off ip6tables 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off iptables 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off irqbalance 0 :off 1 :off 2 :off 3 :on 4 :on 5 :on 6 :off kdump 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off lvm2 -monitor 0 :off 1 :on 2 :on 3 :on 4 :on 5 :on 6 :off mdmonitor 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off messagebus 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off mysqld 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off netconsole 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 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 ntpd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off ntpdate 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off oddjobd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off portreserve 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off postfix 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off psacct 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off quota_nld 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off rdisc 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off restorecond 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off rngd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off rpcbind 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off rpcgssd 0 :off 1 :off 2 :off 3 :on 4 :on 5 :on 6 :off rpcidmapd 0 :off 1 :off 2 :off 3 :on 4 :on 5 :on 6 :off rpcsvcgssd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off rsyslog 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off saslauthd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off smartd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off snmpd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off snmptrapd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off spice -vdagentd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :on 6 :off sshd 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off sssd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off sysstat 0 :off 1 :on 2 :on 3 :on 4 :on 5 :on 6 :off udev -post 0 :off 1 :on 2 :on 3 :on 4 :on 5 :on 6 :off vboxadd 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off vboxadd -service 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off vboxadd -x11 0 :off 1 :off 2 :off 3 :on 4 :off 5 :on 6 :off vncserver 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off wdaemon 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off winbind 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off wpa_supplicant 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off ypbind 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
比如我们需要设置 httpd 服务开启自动启动，可以使用 chkconfig httpd on 命令即可
[root@xiaoluo rc5.d]# chkconfig httpd on [root@xiaoluo rc5.d]# chkconfig --list | grep httpd httpd 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off
如果需要设置成开机不启动，则使用 chkconfig httpd off 命令即可
[root@xiaoluo rc5.d]# chkconfig httpd off [root@xiaoluo rc5.d]# chkconfig --list | grep httpd httpd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
三、xinetd
其实对于上面通过 S有stem V来管理的一些服务都属于Linux系统的常驻运行的服务，其实在Linux系统中还有许多不常驻的一些服务，例如 telnet、rsync服务，这些服务则是通过 xinetd 这个服务来进行管理的。
xinetd 控制的就是那些不常驻的服务，功能较为简单的服务
xinetd其实自己本身就是作为一个系统的常驻的服务运行在后台，而xinetd所控制的服务在没有连接请求的时候是不运行的，所有xinetd控制的服务的连接请求都会提交给xinetd来进行代理
xinetd在收到一个请求后，会根据请求的协议及服务启动相应的服务进程，进程处理完后请求就会结束
xinetd本身就是一个系统服务，通过 System V来对其进行管理，在CentOS6/RHEL6中，xinetd服务默认是没有安装的，我们若要使用该服务，首先需要安装它
[root@xiaoluo ~]# yum install xinetd Loaded plugins: fastestmirror, refresh - packagekit, security Loading mirror speeds from cached hostfile * base: mirror01.idc.hinet.net * extras: mirror01.idc.hinet.net * updates: mirror01.idc.hinet.net base | 3.7 kB 00 : 00 extras | 3.5 kB 00 : 00 updates | 3.4 kB 00 : 00 Setting up Install Process Resolving Dependencies --> Running transaction check ---> Package xinetd.x86_64 2 : 2.3 . 14 - 38 .el6 will be installed --> Finished Dependency Resolution Dependencies Resolved ================================================================================ Package Arch Version Repository Size ================================================================================ Installing: xinetd x86_64 2 : 2.3 . 14 - 38 .el6 base 121 k Transaction Summary ================================================================================ Install 1 Package(s) Total download size: 121 k Installed size: 259 k Is this ok [y / N]: y Downloading Packages: xinetd - 2.3 . 14 - 38 .el6.x86_64.rpm | 121 kB 00 : 01 Running rpm_check_debug Running Transaction Test Transaction Test Succeeded Running Transaction Installing : 2 :xinetd- 2.3 . 14 - 38 .el6.x86_64 1 / 1 Verifying : 2 :xinetd- 2.3 . 14 - 38 .el6.x86_64 1 / 1 Installed: xinetd.x86_64 2 : 2.3 . 14 - 38 .el6 Complete !
在我们安装好我们的xinetd服务以后，我们这时再通过 chkconfig --list 命令来查看所有的服务启动设置
[root@xiaoluo ~]# chkconfig -- list
NetworkManager 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off
abrt -ccpp 0 :off 1 :off 2 :off 3 :on 4 :off 5 :on 6 :off
abrtd 0 :off 1 :off 2 :off 3 :on 4 :off 5 :on 6 :off
acpid 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
auditd 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off
autofs 0 :off 1 :off 2 :off 3 :on 4 :on 5 :on 6 :off
blk -availability 0 :off 1 :on 2 :on 3 :on 4 :on 5 :on 6 :off
bluetooth 0 :off 1 :off 2 :off 3 :on 4 :on 5 :on 6 :off
certmonger 0 :off 1 :off 2 :off 3 :on 4 :on 5 :on 6 :off
cpuspeed 0 :off 1 :on 2 :on 3 :on 4 :on 5 :on 6 :off
crond 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off
cups 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off
dnsmasq 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
firstboot 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
haldaemon 0 :off 1 :off 2 :off 3 :on 4 :on 5 :on 6 :off
htcacheclean 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
httpd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
ip6tables 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off
iptables 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off
irqbalance 0 :off 1 :off 2 :off 3 :on 4 :on 5 :on 6 :off
kdump 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
lvm2 -monitor 0 :off 1 :on 2 :on 3 :on 4 :on 5 :on 6 :off
mdmonitor 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off
messagebus 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off
mysqld 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off
netconsole 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 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
ntpd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
ntpdate 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
oddjobd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
portreserve 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off
postfix 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off
psacct 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
quota_nld 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
rdisc 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
restorecond 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
rngd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
rpcbind 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off
rpcgssd 0 :off 1 :off 2 :off 3 :on 4 :on 5 :on 6 :off
rpcidmapd 0 :off 1 :off 2 :off 3 :on 4 :on 5 :on 6 :off
rpcsvcgssd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
rsyslog 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off
saslauthd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
smartd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
snmpd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
snmptrapd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
spice -vdagentd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :on 6 :off
sshd 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off
sssd 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
sysstat 0 :off 1 :on 2 :on 3 :on 4 :on 5 :on 6 :off
udev -post 0 :off 1 :on 2 :on 3 :on 4 :on 5 :on 6 :off
vboxadd 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off
vboxadd -service 0 :off 1 :off 2 :on 3 :on 4 :on 5 :on 6 :off
vboxadd -x11 0 :off 1 :off 2 :off 3 :on 4 :off 5 :on 6 :off
vncserver 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
wdaemon 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
winbind 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
wpa_supplicant 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
xinetd 0 :off 1 :off 2 :off 3 :on 4 :on 5 :on 6 :off
ypbind 0 :off 1 :off 2 :off 3 :off 4 :off 5 :off 6 :off
xinetd based services:
chargen - dgram: off
chargen - stream: off
daytime - dgram: off
daytime - stream: off
discard - dgram: off
discard - stream: off
echo - dgram: off
echo - stream: off
rsync: off
tcpmux - server: off
time - dgram: off
time -stream: off
我们看到，在安装了xinetd服务以后，其下面出现了一些其他的服务选项，例如rsync，chargen-dgram等这些服务，这些服务都是系统的一些不常驻服务，都是通过xinetd这个服务来对其进行管理的
xinetd服务的配置文件是 /etc/xinetd.conf
[root@xiaoluo ~]# cat /etc/ xinetd.conf
#
# This is the master xinetd configuration file . Settings in the
# default section will be inherited by all service configurations
# unless explicitly overridden in the service configuration. See
# xinetd.conf in the man pages for a more detailed explanation of
# these attributes.
defaults
{
# The next two items are intended to be a quick access place to
# temporarily enable or disable services.
#
# enabled =
# disabled =
# Define general logging characteristics.
log_type = SYSLOG daemon info
log_on_failure = HOST
log_on_success = PID HOST DURATION EXIT
# Define access restriction defaults
#
# no_access =
# only_from =
# max_load = 0
cps = 50 10
instances = 50
per_source = 10
# Address and networking defaults
#
# bind =
# mdns = yes
v6only = no
# setup environmental attributes
#
# passenv =
groups = yes
umask = 002
# Generally, banners are not used. This sets up their global defaults
#
# banner =
# banner_fail =
# banner_success =
}
includedir /etc/xinetd.d
对于由xinetd控制的那些不常驻服务，它们的配置文件是存放在 /etc/xinetd.d/ 这个目录下与该服务名字相同的文件
[root@xiaoluo ~]# cd /etc/xinetd.d/ [root@xiaoluo xinetd.d]# ll total 48 -rw-------. 1 root root 1157 Feb 22 11 : 03 chargen- dgram -rw-------. 1 root root 1159 Feb 22 11 : 03 chargen- stream -rw-------. 1 root root 1157 Feb 22 11 : 03 daytime- dgram -rw-------. 1 root root 1159 Feb 22 11 : 03 daytime- stream -rw-------. 1 root root 1157 Feb 22 11 : 03 discard- dgram -rw-------. 1 root root 1159 Feb 22 11 : 03 discard- stream -rw-------. 1 root root 1148 Feb 22 11 : 03 echo - dgram -rw-------. 1 root root 1150 Feb 22 11 : 03 echo - stream -rw-r--r--. 1 root root 332 Apr 3 2012 rsync -rw-------. 1 root root 1212 Feb 22 11 : 03 tcpmux- server -rw-------. 1 root root 1149 Feb 22 11 : 03 time - dgram -rw-------. 1 root root 1150 Feb 22 11 : 03 time -stream
同样这些配置文件的配置也有固定的格式，例如rsync这个服务的配置文件信息为：
[root@xiaoluo xinetd.d]# cat rsync
# default: off
# description: The rsync server is a good addition to an ftp server, as it # allows crc checksumming etc.
service rsync
{
disable = yes
flags = IPv6
socket_type = stream
wait = no
user = root
server = /usr/bin/ rsync
server_args = -- daemon
log_on_failure += USERID
}
本篇随笔主要讲解了Linux系统服务的基础知识、System V与Xinetd的概念，以及通过 servcie 命令来启动某一服务，通过 chkconfig 命令来设置服务是否开机启动
分类: Linux
标签: linux , CentOS
作者： Leo_wl
出处： http://HdhCmsTestcnblogs测试数据/Leo_wl/
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