服務列表好辦，chkconfig --list 就有了，但是他們都是做什麼用的，系統中是否用得到，怎麼查？
1、man 服務名
最廣泛使用的查詢方式man
比如
# man abrtd
ABRTD(8) ABRT Manual ABRTD(8)
NAME
abrtd - automated bug reporting tool麓s daemon.
SYNOPSIS
abrtd [-dsv[v]...]
DESCRIPTION
abrtd is a daemon that watches for application crashes. When a crash
occurs, it collects the problem data (core file, application鈥檚 command
line etc.) and takes action according to the type of application that
crashed and according to the configuration in the abrt.conf config
file. There are plugins for various actions: for example to report the
crash to Bugzilla, to mail the report, or to transfer the report via
FTP or SCP. See the manual pages for the respective plugins.
2、rpm -qi
當然，也會有一些服務通過man查詢不到， 比如 blk-availability 、 abrt-ccpp。
我們可以通過啟動腳本對應的rpm包來查詢，知道這個rpm包的作用，也就知道這個服務的作用了。
rpm -qi `rpm -qf /etc/rc.d/init.d/服務名` # 注意是反引號
看Description部分，一般就是這個rpm包的作用了，至少能看出來和哪些功能相關。
[root@localhost ~]# rpm -qi `rpm -qf /etc/rc.d/init.d/blk-availability`
Name : lvm2 Relocations: (not relocatable)
Version : 2.02.98 Vendor: CentOS
Release : 9.el6 Build Date: Fri 22 Feb 2013 02:21:40 PM CST
Install Date: Wed 19 Mar 2014 05:06:26 PM CST Build Host: c6b8.bsys.dev.centos.org
Group : System Environment/Base Source RPM: lvm2-2.02.98-9.el6.src.rpm
Size : 1417702 License: GPLv2
Signature : RSA/SHA1, Sun 24 Feb 2013 01:39:56 AM CST, Key ID 0946fca2c105b9de
Packager : CentOS BuildSystem <http://bugs.centos.org>
URL : http://sources.redhat.com/lvm2
Summary : Userland logical volume management tools
Description :
LVM2 includes all of the support for handling read/write operations on
physical volumes (hard disks, RAID-Systems, magneto optical, etc.,
multiple devices (MD), see mdadd(8) or even loop devices, see
losetup(8)), creating volume groups (kind of virtual disks) from one
or more physical volumes and creating one or more logical volumes
(kind of logical partitions) in volume groups.
