Doing It Again with Yum
--《Hands-on Guide to the Red Hat Exams RHCSA and RHCECert Guide and Lab Manual》
--《RHCE7》
Syntax:
yum [options] command
Options:
| 参数 | 含义 |
|---|---|
| -c | Specifies the location of the config file |
| -q | Specifies quiet, no output |
| -y | Indicates to always answer yes to prompts |
| -v | Provides verbose output |
Commands:
| 命令 | 含义 |
|---|---|
| clean | Removes cached data |
| erase | Removes a package from the system |
| grouplist | Displays available package groups |
| groupinstall | Installs the packages within a group |
| info | Displays information about a package |
| install | Installs a package on the system |
| search | Enables you to search for a package |
| update | Updates a package |
Specifying Which Repository to Use
| 参数 | 含义 |
|---|---|
| [label] | The .repo file can contain different repositories, each section starting with a label that identifies the specific repository. |
| name= | Use this to specify the name of the repository you want to use. |
| baseurl= | Contains the URL that points to the specific repository location. |
Key Options in .repo Files
| Option | Explanation |
|---|---|
| [label] | The label used as an identifier in the repository file. |
| name= | The name of the repository. |
| mirrorlist= | Refers to a URL where information about mirror servers for this server can be obtained. Typically used for big online repositories only. |
| baseurl= | The base URL where to go to find the RPM packages |
| gpgcheck= | Set to 1 if a GPG integrity check needs to be performed on the packages. If set to 1, a gpgkey is required. |
| gpgkey= | Specifies the location of the GPG key that is used to check package integrity. |
When using a URL, two components are used. First, the URI identifies the protocol to be used and is in the format protocol://, such as http://, ftp:// or file://. Following the URI is the exact location on that URL. That can be the name of a web server or an FTP server, including the subdirectory where the files are found. If the URL is file based, the location on the file system starts with a / as well. Therefore, for a file system-based URL, there will be three slashes in the baseurl, such as baseurl:/// repo, which refers to the directory /repo on the local file system.
Repository Types and Their Support Status
| Type | Description |
|---|---|
| base | This is the base repository that contains all essential Red Hat software. Its packages are fully supported. |
| updates | A specific repository that contains updates only. |
| optional | This repository contains packages that are provided for the convenience of Red Hat customers. The packages in this repository are open source and not supported by Red Hat. |
| supplementary | This repository contains packages that are provided for the convenience of Red Hat customers. The packages in this repository are proprietary and not supported by Red Hat. |
| extras | This repository contains packages that are provided for the convenience of Red Hat customers. Software in this repository comes from different sources and is not supported by Red Hat. |
Exercise 11.1 Creating Your Own Repository
In this exercise, you learn how to create your own repository. To perform this exer- cise, you need to have access to the CentOS installation disk or ISO file.
- Insert the installation disk in your virtual machine. This mounts it on the direc- tory /run/media/user/CentOS 7 x86_64. Alternatively, you can manually mount the ISO on the /mnt directory, using mount -o loop /path/to/centos.iso /mnt .
- Type mkdir /repo to create a directory /repo that can be used as repository.
- If you want to create a complete repository, containing all the required files, type cp $MOUNTPATH/Packages/* repo . (Replace $MOUNTPATH with the name of the directory on which the installation disk is mounted.) If you do not need a complete repository, you can copy just a few files from the installa- tion disk to the /repo directory.
- Type yum install -y createrepo to ensure that the createrepo RPM package is installed.
- Type createrepo /repo . This generates the repository metadata, which allows you to use your own repository.
- Now that you have created your own repository, you might as well start using it. In the /etc/yum.repos.d directory, create a file with the name my.repo. Make sure this file has the following contents: [myrepo] name=myrepo baseurl=file:///repo
- Type yum repolist to verify the availability of the newly created repository. It should show the name of the myrepo repository, including the number of pack- ages that is offered through this repository (see Listing 11.3 ).
Exercise 11.3 Using yum for Package Management
In this exercise, you use yum for common package management tasks.
- Type yum repolist to show a list of the current repositories that your system is using.
- Type yum search xeyes . This will give no matching result.
- Type yum provides */xeyes . The command shows that the xorg-x11-apps-
package contains this file. - Install this package using yum install -y xorg-x11-apps . Depending on your current configuration, you might notice that quite a few dependencies have to be installed also.
- Type yum list xorg-x11-apps . You see that the package is listed as installed.
- Type yum history and notice the number of the last yum command you used.
- Type yum history undo
(where is replaced with the number that you found in step 6). This undoes the last action, so it removes the package you just installed. - Repeat the yum list xorg-x11-apps command. The package is now listed as available but not as installed.