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This article will explain in detail what is the rpm package management system in RedHat Linux. The content of the article is of high quality, so the editor will share it with you for reference. I hope you will have a certain understanding of the relevant knowledge after reading this article.

Two kinds of package management methods are popular in the linux world, which are rpm of redhat system and deb of debian system. Among them, rpm is more widely used, and I intend to introduce the package management mechanism of rpm in detail in several chapters.

Package management is a way used by the operating system to maintain the versions of various components. For software publishers, making their own programs in standard rpm format will also make it very easy to install, upgrade and uninstall programs. Therefore, almost all popular programs under linux have packages in rpm format, some are packaged by publishers themselves, and some third parties provide rpm packages. For example, rpm in the redhat distribution is packaged by redhat. They regularly play patch, upgrade and maintain dependencies between packages. The rpm packages they produce are the most trustworthy. In addition, http://dag.wieers.com/rpm/ also offers a lot of newer rpm packages, and many packages that can't be found officially in redhat can be found here.

Installation function of RPM

First introduce the installation of rpm, the basic installation commands are as follows

The code is as follows:

Rpm-ivh xxxxxxx.rpm

I for installation, e for uninstall, v for installation, h for progress of # style

Here's a simple example:

The code is as follows:

[leconte@localhost soft] $sudo rpm-ivh enca-1.9-4.el5.rf.i386.rpm

Warning: enca-1.9-4.el5.rf.i386.rpm: Header V3 DSA signature: NOKEY, key ID 6b8d79e6

Preparing... # [100%]

1:enca # # [100%]

The rpm package is installed in this way, but in many cases, it is not so smooth. Because there may be dependencies between rpm packages, you cannot continue to install them by default if the dependencies cannot be satisfied. For example, if a package has already been installed, it is impossible to continue if you want to install it again. In this case, it can be enforced with some parameters, but the consequence of enforcement may be that the installed program cannot be used properly because it depends on packages that are not provided by your system.

The parameters commonly used during installation are as follows:

-- test tests the installation, not the actual installation, but just whether it can be installed.

Nodeps ignores dependencies and forcibly installs

-- force forces the replacement of an existing version

-- noscripts installs files only and does not execute additional scripts

Here is an example of a forced installation. "

The code is as follows:

[leconte@localhost soft] $sudo rpm-ivh awstats-6.9-1.noarch.rpm

Error: Failed dependencies:

Perl (LWP::UserAgent) is needed by awstats-6.9-1.noarch

[leconte@localhost soft] $sudo rpm-ivh awstats-6.9-1.noarch.rpm-- nodeps

Preparing... # [100%]

1:awstats # # [100%]

The PERL module that awstats depends on, LWP::UserAgent, is not installed, so it cannot be installed by default, but it can be forcibly installed through nodeps, and LWP::UserAgent can be installed later through cpan. In other words, if you know what you're doing, then forced installation is not scary.

It is important to note that both the installation and uninstallation of the rpm package require saving information in the system's rpm database, so root permissions are required.

Query function of RPM

Then introduce the query function of rpm, query is our most commonly used function, such as querying which files are contained in a package, which package a file belongs to, and the dependencies between packages, and so on.

The-Q parameter of rpm is used to query, and it should be clear that rpm can query both packages installed on the system and an uninstalled rpm package. When a rpm package is installed on the system, the installation information is usually saved in the local / var/lib/rpm/ directory, and the data is saved as berkeley DB. This can be verified by looking at the type of / var/lib/rpm/Packages file.

The code is as follows:

[leconte@localhost rpm] $file / var/lib/rpm/Packages

/ var/lib/rpm/Packages: Berkeley DB (Hash, version 8, native byte-order)

The query in this case is actually a read access to bdb. To query an uninstalled rpm package, you need to be clear in the first place that you get the information by reading the rpm package itself.

Let me briefly list some of the most commonly used query functions in rpm.

1.rpm-qa is used to query all packages installed on the system. A stands for all.

2.rpm-ql [package name] is used to query the list of files in a package, such as the contents contained in the package passwd.

The code is as follows:

[leconte@localhost rpm] $rpm-ql passwd

/ etc/pam.d/passwd

/ usr/bin/passwd

/ usr/share/man/man1/passwd.1.gz

3.rpm-qi [package name] is used to query package information, including the package introduction, author, package date and other important information.

4.rpm-qf [filename] is used to query the rpm package to which a file belongs, for example:

The code is as follows:

[leconte@localhost rpm] $rpm-qf / etc/passwd

Setup-2.5.58-4.el5

The system configuration file / etc/passwd belongs to the package setup.

5.rpm-qV [package name] is used to verify the status of the files installed in a package. If the current file size, md5 and the information stored in the database at the time of installation are inconsistent, the command will list the inconsistent files. This command is very helpful for troubleshooting when something goes wrong with the system.

The above are some of the most commonly used query commands, all for the query system rpm package. If you want to query an uninstalled rpm package, you only need to add the p parameter and the package path. For example, query the information of the package perl-Git-1.5.5.6-4.el5.i386.rpm:

The code is as follows:

[leconte@localhost soft] $rpm-qip perl-Git-1.5.5.6-4.el5.i386.rpm

Warning: perl-Git-1.5.5.6-4.el5.i386.rpm: Header V3 DSA signature: NOKEY, key ID 217521f6

Name: perl-Git Relocations: (not relocatable)

Version: 1.5.5.6 Vendor: Fedora Project

Release: 4.el5 Build Date: Friday, June 19, 2009, 21:28:05

Install Date: (not installed) Build Host: xenbuilder2.fedora.redhat.com

Group: Development/Libraries Source RPM: git-1.5.5.6-4.el5.src.rpm

Size: 24878 License: GPL

Signature: DSA/SHA1, Saturday, June 20, 2009, 04:07:18, Key ID 119cc036217521f6

Packager: Fedora Project

URL: http://kernel.org/pub/software/scm/git/

Summary: Perl interface to Git

Description:

Perl interface to Git.

Dependencies of RPM packages

Dependencies between rpm packages are maintained, which is a feature of the package management system. We have all experienced situations where a package is installed and cannot be installed because of a lack of dependencies. Later, the emergence of yum can solve this problem to some extent, but it is still necessary for us to understand the details behind the rpm dependency.

Anyone who has typed the rpm package knows that the spec configuration file of the package often needs to clearly write out the package name or file name on which the package depends, and may also need to clearly write out what the package provides. This content may be a dynamic library or some other name, not necessarily a file name. Each package relies on this content to establish a dependency relationship, each package provides some content and depends on some other content, the whole system is formed in such an interdependence.

Before looking at specific examples, let's introduce a few instructions:

Rpm-qR [package name] can be used to query what a specified package depends on.

Rpm-Q-provides [package name] can be used to query the content provided by a specified package.

Rpm-Q-whatprovides [content] can be used to query which package provides the specified content.

Rpm-Q-whatrequires [content] can be used to see which packages depend on the specified content.

For example, we take the package time as an example to query, and the results are as follows:

The code is as follows:

[leconte@localhost soft] $rpm-qR time

/ bin/sh

/ bin/sh

/ sbin/install-info

Libc.so.6

Libc.so.6 (GLIBC_2.0)

Libc.so.6 (GLIBC_2.1)

Libc.so.6 (GLIBC_2.3.4)

Rpmlib (CompressedFileNames)

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