Why the system cannot be updated using yum

Why the system cannot be updated using yum
Trixbox is an open source PBX distribution edition that installs all dependent software on centeros (a Linux distribution edition, to package an ISO image, you only need to install

In minutes, You Can format a PC and install it as a home PBX. however, if I want to develop on top, I need some third-party software, such as GCC, kernel-devel (for compilation), subversion (for obtaining an updated

Software packages); trixbox is not installed by default.
So I used the yum management software and referred to the use of yum, and found that it is very powerful,
On the one hand, he can manage software:
1. Install new software
2. Update Software
3. Remove Software
You can also use Yum search software.
Of course, the most common user can use Yum to update your system. This function is equivalent to Automatic windows updates and can be patched for your system.

Before using it, we should first understand the repository. Generally, members of the community will maintain a software warehouse suitable for the operating system. In addition, some software authors may also provide a separate repository. And

The information is stored in the/etc/yum. Repos. D in your system and several description files in the directory. Repository maintainers generally publish their repository description files on their websites. The repository description file name ends with. Repo. You must have

Root permission can be used to add files to this directory.

The problem I encountered this time was that when I used Yum-y update to update my system, the following report was reported:
Http://download.skype.com/linux/repo...ta/repomd.xml: [errno 14] HTTP Error 404: SERVER: nginx/0.5.14
Trying other mirror.
Error: cannot open/read repomd. xml file for repository: Skype)
Of course, the literal meaning is that the target server cannot be found, that is, the software in the software warehouse has been obtained. But I am also confused, why should I go to a Skype website to update the software? Later, I checked the information and found someone was like this.

Reply:
You have installed a lot of useless repos and yum is not working properly because of that.
Post the output of this
That is to say, you have configured too many target software warehouse libraries, causing confusion in Yum searching. Sure enough, I checked:
Ls/etc/yum. Repos. d
Find a lot of *. Repo, try to open one, and see it is similar to the configuration of an address. We can see two seemingly official configuration files, which are retained and all other configuration files are deleted.
Then execute Yum clean all
OK, and then execute the Yum-y update command. I rely on the command. If it succeeds, I will continue to download and wait for n minutes.
Yum does not require any routine maintenance. To ensure the operation speed of yum, you should disable or delete warehouses that are no longer needed and delete files in the yum cache, this saves hard disk space.
You can set enable = 0 in the repository description file. The yum tool ignores the description file containing this setting.
To completely delete a repository, you can delete related files from the/etc/yum. Repos. d/directory and delete related cache directories from/var/Cache/yum.
By default, yum retains the software packages and software information files it has downloaded, so that you do not need to download them again next time. To delete the software file information, run the following command:
Yum clean Headers
To delete all the software packages in the cache, run the following command:
Yum clean packages