一、 yum的一点小用法；
1、查询软件包；
面对成千上万的软件，我们可能无从下手，有时也不知道它的文件名；这时就要用到查询；我们可以用 yum list 来列出yum升级源上的包有文件；然后我们再来查看 info有以下几个组合可以用；比如；
[root@localhost]# yum list |more
在显示的软件列表中，会有软件名称、版本、是否安装等；仔细的看一下吧。熟悉了就好了。也没有什么难的。
[root@localhost]# yum list |more
Setting up repositories
Reading repository metadata in from local files
Installed Packages
4Suite.i386 1.0-8.b1 installed
Canna.i386 3.7p3-13 installed
Canna-devel.i386 3.7p3-13 installed
如果想知道软件的详细信息，可能得用上info参数了。比如：
用法：
[root@localhost]# yum info 软件名
比如：
[root@localhost]# yum info bmp-mp3
Setting up repositories
updates-released 100% |=========================| 951 B 00:00
extras 100% |=========================| 1.1 kB 00:00
base 100% |=========================| 1.1 kB 00:00
freshrpms 100% |=========================| 951 B 00:00
Reading repository metadata in from local files
Installed Packages
Name : bmp-mp3
Arch : i386
Version: 0.9.7
Release: 1.2.fc4
Size : 234 k
Repo : freshrpms
Summary: MP3 playback plugin for the Beep Media Player
Description:
This package contains an MP3 playback plugin for BMP (Beep Media Player),
a media player that uses a skinned user interface based on Winamp 2.x skins,
and is based on ("forked off") XMMS.
在上面的例子中，如果Repo : freshrpms是这样的，表示您的系统没有安装这个软件，如果显示的是：Repo : installed，表示已经安装了。
查询软件包，也可以再加参数 grep ，比如我们想查询升级源上是否有内核的新版本，则我们可以用下面的命令查询；当然您也可以用 [root@localhost]# yum search kernel |more ，也就是yum --help提供的参数，也是一样的；
[root@localhost]# yum list |grep kernel
我们看一下机器工作的结果，如下：
[root@localhost]# yum list |grep kernel
GFS-kernel.i686 2.6.11.8-20050601.1526 installed
cman-kernel.i686 2.6.11.5-20050601.1526 installed
dlm-kernel.i686 2.6.11.5-20050601.1526 installed
gnbd-kernel.i686 2.6.11.2-20050420.1331 installed
kernel.i686 2.6.11-1.1369_FC4 installed
kernel-devel.i686 2.6.11-1.1369_FC4 installed
kernel-doc.noarch 2.6.11-1.1369_FC4 installed
GFS-kernel.i586 2.6.11.8-20050601.1526 base
GFS-kernel-debuginfo.i686 2.6.11.8-20050601.1526 updates-released
GFS-kernel-debuginfo.i586 2.6.11.8-20050601.1526 updates-released
GFS-kernel-smp.i686 2.6.11.8-20050601.1526 base
GFS-kernel-xen0.i686 2.6.11.8-20050601.1526 base
GFS-kernel-xenU.i686 2.6.11.8-20050601.1526 base
cman-kernel.i586 2.6.11.5-20050601.1526 updates-released
cman-kernel.i686 2.6.11.5-20050601.1526 updates-released
cman-kernel-debuginfo.i586 2.6.11.5-20050601.1526 updates-released
cman-kernel-debuginfo.i686 2.6.11.5-20050601.1526 updates-released
cman-kernel-smp.i686 2.6.11.5-20050601.1526 updates-released
cman-kernel-xen0.i686 2.6.11.5-20050601.1526 updates-released
cman-kernel-xenU.i686 2.6.11.5-20050601.1526 updates-released
dlm-kernel.i686 2.6.11.5-20050601.1526 updates-released
dlm-kernel.i586 2.6.11.5-20050601.1526 updates-released
dlm-kernel-debuginfo.i586 2.6.11.5-20050601.1526 updates-released
dlm-kernel-debuginfo.i686 2.6.11.5-20050601.1526 updates-released
dlm-kernel-smp.i686 2.6.11.5-20050601.1526 updates-released
dlm-kernel-xen0.i686 2.6.11.5-20050601.1526 updates-released
dlm-kernel-xenU.i686 2.6.11.5-20050601.1526 updates-released
gnbd-kernel.i686 2.6.11.2-20050420.1331 updates-released
gnbd-kernel.i586 2.6.11.2-20050420.1331 updates-released
gnbd-kernel-debuginfo.i586 2.6.11.2-20050420.1331 updates-released
gnbd-kernel-debuginfo.i686 2.6.11.2-20050420.1331 updates-released
gnbd-kernel-smp.i686 2.6.11.2-20050420.1331 updates-released
gnbd-kernel-xen0.i686 2.6.11.2-20050420.1331 updates-released
gnbd-kernel-xenU.i686 2.6.11.2-20050420.1331 updates-released
kernel.i586 2.6.12-1.1398_FC4 updates-released
kernel.i686 2.6.12-1.1398_FC4 updates-released
kernel-debuginfo.i686 2.6.12-1.1398_FC4 updates-released
kernel-debuginfo.i586 2.6.12-1.1398_FC4 updates-released
kernel-devel.i586 2.6.12-1.1398_FC4 updates-released
kernel-devel.i686 2.6.12-1.1398_FC4 updates-released
kernel-doc.noarch 2.6.12-1.1398_FC4 updates-released
kernel-smp.i686 2.6.12-1.1398_FC4 updates-released
kernel-smp-devel.i686 2.6.12-1.1398_FC4 updates-released
kernel-xen0.i686 2.6.12-1.1398_FC4 updates-released
kernel-xen0-devel.i686 2.6.12-1.1398_FC4 updates-released
kernel-xenU.i686 2.6.12-1.1398_FC4 updates-released
kernel-xenU-devel.i686 2.6.12-1.1398_FC4 updates-released
比如我们用的机器是单处理器的X86机，想看一下是否有新内核可用。所以咱们试一下下面的这个。看是否已经有了新内核可以升级的；
[root@localhost]# yum info kernel.i686
Setting up repositories
updates-released 100% |=========================| 951 B 00:00
extras 100% |=========================| 1.1 kB 00:00
base 100% |=========================| 1.1 kB 00:00
freshrpms 100% |=========================| 951 B 00:00
Reading repository metadata in from local files
Installed Packages
Name : kernel
Arch : i686
Version: 2.6.11
Release: 1.1369_FC4
Size : 37 M
Repo : installed
Summary: Linux 内核(Linux 操作系统的核心)。
Description:
kernel 软件包包含 Linux 内核 (vmlinuz)，Red Hat Linux
操作系统的核心。内核处理操作系统的基本功能：
分配内存、处理分配、设备的输入和输出等等。
Available Packages
Name : kernel
Arch : i686
Version: 2.6.12
Release: 1.1398_FC4
Size : 14 M
Repo : updates-released
Summary: The Linux kernel (the core of the Linux operating system)
Description:
The kernel package contains the Linux kernel (vmlinuz), the core of any
Linux operating system. The kernel handles the basic functions
of the operating system: memory allocation, process allocation, device
input and output, etc.
通过上面的信息，我们可以看到 2.6.11的是已经安装了，因为已经显示的是Repo : installed ，下面还有一个Version: 2.6.12 ，告诉我们是Repo : updates-released，看来这个是升级用的了。
[root@localhost]# yum update kernel
升级内核全景如下：
[root@localhost]# yum update kernel
Setting up Upgrade Process
Setting up repositories
updates-released 100% |=========================| 951 B 00:00
extras 100% |=========================| 1.1 kB 00:00
base 100% |=========================| 1.1 kB 00:00
freshrpms 100% |=========================| 951 B 00:00
Reading repository metadata in from local files
Resolving Dependencies
--> Populating transaction set with selected packages. Please wait.
---> Downloading header for kernel to pack into transaction set.
kernel-2.6.12-1.1398_FC4. 100% |=========================| 174 kB 00:18
---> Package kernel.i686 0:2.6.12-1.1398_FC4 set to be installed
--> Running transaction check
Dependencies Resolved
=============================================================================
Package Arch Version Repository Size
=============================================================================
Installing:
kernel i686 2.6.12-1.1398_FC4 updates-released 14 M
Transaction Summary
=============================================================================
Install 1 Package(s)
Update 0 Package(s)
Remove 0 Package(s)
Total download size: 14 M
Is this ok [y/N]:
是不是升级，只需要在 Is this ok [y/N]:行的后面输入y或者N；
对于软件包的查询，还有，比如：
[root@localhost]# yum list available 列出所有升级源上的包；
[root@localhost]# yum list updates 列出所有升级源上的可以更新包；
[root@localhost]# yum list installed 列出已经安装的包；
yum 的命令支持通配符； 比如；
[root@localhost]# yum list mp* |more
Setting up repositories
Reading repository metadata in from local files
Installed Packages
mpage.i386 2.5.4-5 installed
Available Packages
mpc.i386 0.11.2-3 extras
mpeg2dec.i386 0.4.0-5b.2.fc4 freshrpms
mpeg2dec-devel.i386 0.4.0-5b.2.fc4 freshrpms
mpg321.i386 0.2.10-6.2.fc4 freshrpms
mplayer.i386 1.0-0.16.pre7.2.fc4 freshrpms
mplayer-docs.i386 1.0-0.16.pre7.2.fc4 freshrpms
mplayer-fonts.noarch 1.1-3.fc freshrpms
mplayer-skins.noarch 1.7-1.fc freshrpms
[root@localhost]#
2.安装和升级软件包；
安装和升级分别是 install 和 update 参数；比如；
[root@localhost]# yum update firefox
这样我们就可以升级 firefox了。
[root@localhost]# yum update firefox
Setting up Update Process
Setting up repositories
updates-released 100% |=========================| 951 B 00:00
extras 100% |=========================| 1.1 kB 00:00
base 100% |=========================| 1.1 kB 00:03
freshrpms 100% |=========================| 951 B 00:02
Reading repository metadata in from local files
Resolving Dependencies
--> Populating transaction set with selected packages. Please wait.
---> Package firefox.i386 0:1.0.6-1.1.fc4 set to be updated
--> Running transaction check
Dependencies Resolved
=============================================================================
Package Arch Version Repository Size
=============================================================================
Updating:
firefox i386 1.0.6-1.1.fc4 updates-released 18 M
Transaction Summary
=============================================================================
Install 0 Package(s)
Update 1 Package(s)
Remove 0 Package(s)
Total download size: 18 M
Is this ok [y/N]:
如果不加参数的 update 会是什么呢？？
[root@localhost]# yum update
试着运行一下看看？会好长时间，对系统进行全面更新，我们要进行y和N了。 