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May the source be with you, but remember the KISS principle ;-)
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(slightly skeptical) Educational society promoting "Back to basics" movement against IT overcomplexity and  bastardization of classic Unix

Software and configuration management using RPM

News Recommended Links Building RPMs Tutorials Reference Cheat sheet  
--aid option Installation/Removal Verification Queries Unpacking and analysis of RPM content RPM-based integrity checking Examples
    Finding orphaned RPMs Removal of RPMs
YUM

YAST

RPM-related PERL Modules and Utilities Autoupdates   Admin Horror Stories Unix History Humor Etc

RPM repositories and yum provide ready made and available in default Red Hat (and derivatives) distribution infrastructure for distribution of custom patches and configuration files. The only problem is to learn how to use them. here this page might help.   Many people are afraid of even touching this area because it looks like building your own RPMs is very complex. It is not. It is actually less complex that it sound.

To distribute a set of patches to all your servers you need to create a custom RPM with those patches. 

The simplest way to create your own RPM is to start with somebody else RPM and modify it for your needs. Source ROMs are better deal.

For testing you can install an rpm to an arbitrary  directory (e.g. /my/targetdir) placing the package files under targetdir and the rpm database in the targetdir/var/rpm directory with something like:

rpm -ivh --nodeps --relocate /=/my/targetdir --root=/my/targetdir mypackage.rpm

rpm2cpio is the tool you'd need, to extract the content of CPIO part of the archive. Midnight commander can extract all other files and actually is a preferable tool for working with RPMs.

Suse has unrpm, which been part of the distribution for a long time  See UnRpm Issue 19

Midnight commander allows you to  view the files inside the rpm, viewing not just the directory structure, but the init script itself


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[Jun 10, 2020] A Beginners Guide to Snaps in Linux - Part 1 by Aaron Kili

Jun 05, 2020 | www.tecmint.com
Linux Certifications - RHCSA / RHCE Certification | Ansible Automation Certification | LFCS / LFCE Certification In the past few years, the Linux community has been blessed with some remarkable advancements in the area of package management on Linux systems , especially when it comes to universal or cross-distribution software packaging and distribution. One of such advancements is the Snap package format developed by Canonical , the makers of the popular Ubuntu Linux . What are Snap Packages?

Snaps are cross-distribution, dependency-free, and easy to install applications packaged with all their dependencies to run on all major Linux distributions. From a single build, a snap (application) will run on all supported Linux distributions on desktop, in the cloud, and IoT. Supported distributions include Ubuntu, Debian, Fedora, Arch Linux, Manjaro, and CentOS/RHEL.

Snaps are secure – they are confined and sandboxed so that they do not compromise the entire system. They run under different confinement levels (which is the degree of isolation from the base system and each other). More notably, every snap has an interface carefully selected by the snap's creator, based on the snap's requirements, to provide access to specific system resources outside of their confinement such as network access, desktop access, and more.

Another important concept in the snap ecosystem is Channels . A channel determines which release of a snap is installed and tracked for updates and it consists of and is subdivided by, tracks, risk-levels, and branches.

The main components of the snap package management system are:

Besides, snaps also update automatically. You can configure when and how updates occur. By default, the snapd daemon checks for updates up to four times a day: each update check is called a refresh . You can also manually initiate a refresh.

How to Install Snapd in Linux

As described above, the snapd daemon is the background service that manages and maintains your snap environment on a Linux system, by implementing the confinement policies and controlling the interfaces that allow snaps to access specific system resources. It also provides the snap command and serves many other purposes.

To install the snapd package on your system, run the appropriate command for your Linux distribution.

------------ [On Debian and Ubuntu] ------------ 
$ sudo apt update 
$ sudo apt install snapd

------------ [On Fedora Linux] ------------
# dnf install snapd                     

------------ [On CentOS and RHEL] ------------
# yum install epel-release 
# yum install snapd             

------------ [On openSUSE - replace openSUSE_Leap_15.0 with the version] ------------
$ sudo zypper addrepo --refresh https://download.opensuse.org/repositories/system:/snappy/openSUSE_Leap_15.0 snappy
$ sudo zypper --gpg-auto-import-keys refresh
$ sudo zypper dup --from snappy
$ sudo zypper install snapd

------------ [On Manjaro Linux] ------------
# pacman -S snapd

------------ [On Arch Linux] ------------
# git clone https://aur.archlinux.org/snapd.git
# cd snapd
# makepkg -si

After installing snapd on your system, enable the systemd unit that manages the main snap communication socket, using the systemctl commands as follows.

On Ubuntu and its derivatives, this should be triggered automatically by the package installer.

$ sudo systemctl enable --now snapd.socket

Note that you can't run the snap command if the snapd.socket is not running. Run the following commands to check if it is active and is enabled to automatically start at system boot.

$ sudo systemctl is-active snapd.socket
$ sudo systemctl status snapd.socket
$ sudo systemctl is-enabled snapd.socket
Check Snapd Service Status <img aria-describedby="caption-attachment-37630" src="https://www.tecmint.com/wp-content/uploads/2020/06/check-if-snapd-socket-is-running.png" alt="Check Snapd Service Status" width="722" height="293" />

Check Snapd Service Status

Next, enable classic snap support by creating a symbolic link between /var/lib/snapd/snap and /snap as follows.

$ sudo ln -s /var/lib/snapd/snap /snap

To check the version of snapd and snap command-line tool installed on your system, run the following command.

$ snap version
Check Snapd and Snap Version <img aria-describedby="caption-attachment-37631" src="https://www.tecmint.com/wp-content/uploads/2020/06/check-snapd-and-snap-version.png" alt="Check Snapd and Snap Version" width="510" height="124" />

Check Snapd and Snap Version How to Install Snaps in Linux

The snap command allows you to install, configure, refresh and remove snaps, and interact with the larger snap ecosystem.

Before installing a snap , you can check if it exists in the snap store. For example, if the application belongs in the category of " chat servers " or " media players ", you can run these commands to search for it, which will query the store for available packages in the stable channel.

$ snap find "chat servers"
$ snap find "media players"
Find Applications in Snap Store <img aria-describedby="caption-attachment-37632" src="https://www.tecmint.com/wp-content/uploads/2020/06/find-snaps.png" alt="Find Applications in Snap Store" width="899" height="515" srcset="https://www.tecmint.com/wp-content/uploads/2020/06/find-snaps.png 899w, https://www.tecmint.com/wp-content/uploads/2020/06/find-snaps-768x440.png 768w" sizes="(max-width: 899px) 100vw, 899px" />

Find Applications in Snap Store

To show detailed information about a snap , for example, rocketchat-server , you can specify its name or path. Note that names are looked for both in the snap store and in the installed snaps.

$ snap info rocketchat-server
Get Info About Application in Snap <img aria-describedby="caption-attachment-37633" src="https://www.tecmint.com/wp-content/uploads/2020/06/get-more-details-about-a-snap.png" alt="Get Info About Application in Snap" width="824" height="485" srcset="https://www.tecmint.com/wp-content/uploads/2020/06/get-more-details-about-a-snap.png 824w, https://www.tecmint.com/wp-content/uploads/2020/06/get-more-details-about-a-snap-768x452.png 768w" sizes="(max-width: 824px) 100vw, 824px" />

Get Info About Application in Snap

To install a snap on your system, for example, rocketchat-server , run the following command. If no options are provided, a snap is installed tracking the " stable " channel, with strict security confinement.

$ sudo snap install rocketchat-server
Install Application from Snap Store <img aria-describedby="caption-attachment-37634" src="https://www.tecmint.com/wp-content/uploads/2020/06/rocketchat-server-snap-installed-successfully.png" alt="Install Application from Snap Store" width="700" height="57" />

Install Application from Snap Store

You can opt to install from a different channel: edge , beta , or candidate , for one reason or the other, using the --edge , --beta , or --candidate options respectively. Or use the --channel option and specify the channel you wish to install from.

$ sudo snap install --edge rocketchat-server        
$ sudo snap install --beta rocketchat-server
$ sudo snap install --candidate rocketchat-server
Manage Snaps in Linux

In this section, we will learn how to manage snaps in Linux system.

Viewing Installed Snaps

To display a summary of snaps installed on your system, use the following command.

$ snap list
List Installed Snaps <img aria-describedby="caption-attachment-37635" src="https://www.tecmint.com/wp-content/uploads/2020/06/list-installed-snaps.png" alt="List Installed Snaps" width="662" height="156" />

List Installed Snaps

To list the current revision of a snap being used, specify its name. You can also list all its available revisions by adding the --all option.

$ snap list mailspring
OR
$ snap list --all mailspring
List All Installation Versions of Snap <img aria-describedby="caption-attachment-37636" src="https://www.tecmint.com/wp-content/uploads/2020/06/list-all-versions-of-a-snap.png" alt="List All Installation Versions of Snap" width="609" height="155" />

List All Installation Versions of Snap Updating and Reverting Snaps

You can update a specified snap, or all snaps in the system if none are specified as follows. The refresh command checks the channel being tracked by the snap and it downloads and installs a newer version of the snap if it is available.

$ sudo snap refresh mailspring
OR
$ sudo snap refresh             #update all snaps on the local system
Refresh a Snap <img aria-describedby="caption-attachment-37637" src="https://www.tecmint.com/wp-content/uploads/2020/06/refresh-a-snap.png" alt="Refresh a Snap" width="591" height="57" />

Refresh a Snap

After updating an app to a new version, you can revert to a previously used version using the revert command. Note that the data associated with the software will also be reverted.

$ sudo snap revert mailspring
Revert a Snap to Older Version <img aria-describedby="caption-attachment-37638" src="https://www.tecmint.com/wp-content/uploads/2020/06/revert-a-snap-to-older-version.png" alt="Revert a Snap to Older Version" width="450" height="56" />

Revert a Snap to Older Version

Now when you check all revisions of mailspring , the latest revision is disabled , a previously used revision is now active.

$ snap list --all mailspring
Check Revision of Snap <img aria-describedby="caption-attachment-37639" src="https://www.tecmint.com/wp-content/uploads/2020/06/snap-reverted-to-older-version.png" alt="Check Revision of Snap " width="601" height="90" />

Check Revision of Snap Disabling/Enabling and Removing Snaps

You can disable a snap if you do not want to use it. When disabled, a snap's binaries and services will no longer be available, however, all the data will still be there.

$ sudo snap disable mailspring

If you need to use the snap again, you can enable it back.

$ sudo snap enable mailspring

To completely remove a snap from your system, use the remove command. By default, all of a snap's revisions are removed.

$ sudo snap remove mailspring

To remove a specific revision, use the --revision option as follows.

$ sudo snap remove  --revision=482 mailspring

It is key to note that when you remove a snap , its data (such as internal user, system, and configuration data) is saved by snapd (version 2.39 and higher) as a snapshot, and stored on the system for 31 days. In case you reinstall the snap within the 31 days, you can restore the data.

Conclusion

Snaps are becoming more popular within the Linux community as they provide an easy way to install software on any Linux distribution. In this guide, we have shown how to install and work with snaps in Linux. We covered how to install snapd , install snaps , view installed snaps, update and revert snaps, and disable/enable and remove snaps.

You can ask questions or reach us via the feedback form below. In the next part of this guide, we will cover managing snaps (commands, aliases, services, and snapshots) in Linux.

[Jun 26, 2019] Linux Package Managers Compared - AppImage vs Snap vs Flatpak

Jun 26, 2019 | www.ostechnix.com

by editor · Published June 24, 2019 · Updated June 24, 2019

Package managers provide a way of packaging, distributing, installing, and maintaining apps in an operating system. With modern desktop, server and IoT applications of the Linux operating system and the hundreds of different distros that exist, it becomes necessary to move away from platform specific packaging methods to platform agnostic ones. This post explores 3 such tools, namely AppImage , Snap and Flatpak , that each aim to be the future of software deployment and management in Linux. At the end we summarize a few key findings.

1. AppImage

AppImage follows a concept called "One app = one file" . This is to be understood as an AppImage being a regular independent "file" containing one application with everything it needs to run in the said file. Once made executable, the AppImage can be run like any application in a computer by simply double-clicking it in the users file system.[1]

It is a format for creating portable software for Linux without requiring the user to install the said application. The format allows the original developers of the software (upstream developers) to create a platform and distribution independent (also called a distribution-agnostic binary) version of their application that will basically run on any flavor of Linux.

AppImage has been around for a long time. Klik , a predecessor of AppImage was created by Simon Peter in 2004. The project was shut down in 2011 after not having passed the beta stage. A project named PortableLinuxApps was created by Simon around the same time and the format was picked up by a few portals offering software for Linux users. The project was renamed again in 2013 to its current name AppImage and a repository has been maintained in GitHub (project link ) with all the latest changes to the same since 2018.[2][3]

Written primarily in C and donning the MIT license since 2013, AppImage is currently developed by The AppImage project . It is a very convenient way to use applications as demonstrated by the following features:

  1. AppImages can run on virtually any Linux system. As mentioned before applications derive a lot of functionality from the operating system and a few common libraries. This is a common practice in the software world since if something is already done, there is no point in doing it again if you can pick and choose which parts from the same to use. The problem is that many Linux distros might not have all the files a particular application requires to run since it is left to the developers of that particular distro to include the necessary packages. Hence developers need to separately include the dependencies of the application for each Linux distro they are publishing their app for. Using the AppImage format developers can choose to include all the libraries and files that they cannot possibly hope the target operating system to have as part of the AppImage file. Hence the same AppImage format file can work on different operating systems and machines without needing granular control.
  2. The one app one file philosophy means that user experience is simple and elegant in that users need only download and execute one file that will serve their needs for using the application.
  3. No requirement of root access . System administrators will require people to have root access to stop them from messing with computers and their default setup. This also means that people with no root access or super user privileges cannot install the apps they need as they please. The practice is common in a public setting (such as library or university computers or on enterprise systems). The AppImage file does not require users to "install" anything and hence users need only download the said file and make it executable to start using it. This removes the access dilemmas that system administrators have and makes their job easier without sacrificing user experience.
  4. No effect on core operating system . The AppImage-application format allows using applications with their full functionality without needing to change or even access most system files. Meaning whatever the applications do, the core operating system setup and files remain untouched.
  5. An AppImage can be made by a developer for a particular version of their application. Any updated version is made as a different AppImage. Hence users if need be can test multiple versions of the same application by running different instances using different AppImages. This is an invaluable feature when you need to test your applications from an end-user POV to notice differences.
  6. Take your applications where you go. As mentioned previously AppImages are archived files of all the files that an application requires and can be used without installing or even bothering about the distribution the system uses. Hence if you have a set of apps that you use regularly you may even mount a few AppImage files on a thumb drive and take it with you to use on multiple computers running multiple different distros without worrying whether they'll work or not.

Furthermore, the AppImageKit allows users from all backgrounds to build their own AppImages from applications they already have or for applications that are not provided an AppImage by their upstream developer.

The package manager is platform independent but focuses primarily on software distribution to end users on their desktops with a dedicated daemon AppImaged for integrating the AppImage formats into respective desktop environments. AppImage is supported natively now by a variety of distros such as Ubuntu, Debian, openSUSE, CentOS, Fedora etc. and others may set it up as per their needs. AppImages can also be run on servers with limited functionality via the CLI tools included.

To know more about AppImages, go to the official AppImage documentation page.


Suggested read:


2. Snappy

Snappy is a software deployment and package management system like AppImage or any other package manager for that instance. It is originally designed for the now defunct Ubuntu Touch Operating system. Snappy lets developers create software packages for use in a variety of Linux based distributions. The initial intention behind creating Snappy and deploying "snaps" on Ubuntu based systems is to obtain a unified single format that could be used in everything from IoT devices to full-fledged computer systems that ran some version of Ubuntu and in a larger sense Linux itself.[4]

The lead developer behind the project is Canonical , the same company that pilots the Ubuntu project. Ubuntu had native snap support from version 16.04 LTS with more and more distros supporting it out of the box or via a simple setup these days. If you use Arch or Debian or openSUSE you'll find it easy to install support for the package manager using simple commands in the terminal as explained later in this section. This is also made possible by making the necessary snap platform files available on the respective repos.[5]

Snappy has the following important components that make up the entire package manager system.[6]

The snapd component is written primarily in C and Golang whereas the Snapcraft framework is built using Python . Although both the modules use the GPLv3 license it is to be noted that snapd has proprietary code from Canonical for its server-side operations with just the client side being published under the GPL license. This is a major point of contention with developers since this involves developers signing a CLA form to participate in snap development.[7]

Going deeper into the finer details of the Snappy package manager the following may be noted:

  1. Snaps as noted before are all inclusive and contain all the necessary files (dependencies) that the application needs to run. Hence, developers need not to make different snaps for the different distros that they target. Being mindful of the runtimes is all that's necessary if base runtimes are excluded from the snap.
  2. Snappy packages are meant to support transactional updates. Such a transactional update is atomic and fully reversible, meaning you can use the application while its being updated and that if an update does not behave the way its supposed to, you can reverse the same with no other effects whatsoever. The concept is also called as delta programming in which only changes to the application are transmitted as an update instead of the whole package. An Ubuntu derivative called Ubuntu Core actually promises the snappy update protocol to the OS itself.[8]
  3. A key point of difference between snaps and AppImages, is how they handle version differences. Using AppImages different versions of the application will have different AppImages allowing you to concurrently use 2 or more different versions of the same application at the same time. However, using snaps means conforming to the transactional or delta update system. While this means faster updates, it keeps you from running two instances of the same application at the same time. If you need to use the old version of an app you'll need to reverse or uninstall the new version. Snappy does support a feature called "parallel install" which will let users accomplish similar goals, however, it is still in an experimental stage and cannot be considered to be a stable implementation. Snappy also makes use of channels meaning you can use the beta or the nightly build of an app and the stable version at the same time.[9]
  4. Extensive support from major Linux distros and major developers including Google, Mozilla, Microsoft, etc.[4]
  5. Snapd the desktop integration tool supports taking "snapshots" of the current state of all the installed snaps in the system. This will let users save the current configuration state of all the applications that are installed via the Snappy package manager and let users revert to that state whenever they desire so. The same feature can also be set to automatically take snapshots at a frequency deemed necessary by the user. Snapshots can be created using the snap save command in the snapd framework.[10]
  6. Snaps are designed to be sandboxed during operation. This provides a much-required layer of security and isolation to users. Users need not worry about snap-based applications messing with the rest of the software on their computer. Sandboxing is implemented using three levels of isolation viz, classic , strict and devmode . Each level of isolation allows the app different levels of access within the file system and computer.[11]

On the flip side of things, snaps are widely criticized for being centered around Canonical's modus operandi . Most of the commits to the project are by Canonical employees or contractors and other contributors are required to sign a release form (CLA). The sandboxing feature, a very important one indeed from a security standpoint, is flawed in that the sandboxing actually requires certain other core services to run (such as Mir) while applications running the X11 desktop won't support the said isolation, hence making the said security feature irrelevant. Questionable press releases and other marketing efforts from Canonical and the "central" and closed app repository are also widely criticized aspects of Snappy. Furthermore, the file sizes of the different snaps are also comparatively very large compared to the app sizes of the packages made using AppImage.[7]

For more details, check Snap official documentation .


Related read:


3. Flatpak

Like the Snap/Snappy listed above, Flatpak is also a software deployment tool that aims to ease software distribution and use in Linux. Flatpak was previously known as "xdg-app" and was based on concept proposed by Lennart Poettering in 2004. The idea was to contain applications in a secure virtual sandbox allowing for using applications without the need of root privileges and without compromising on the systems security. Alex started tinkering with Klik (thought to be a former version of AppImage) and wanted to implement the concept better. Alexander Larsson who at the time was working with Red Hat wrote an implementation called xdg-app in 2015 that acted as a pre-cursor to the current Flatpak format.

Flatpak officially came out in 2016 with backing from Red Hat, Endless Computers and Collabora. Flathub is the official repository of all Flatpak application packages. At its surface Flatpak like the other is a framework for building and packaging distribution agnostic applications for Linux. It simply requires the developers to conform to a few desktop environment guidelines in order for the application to be successfully integrated into the Flatpak environment.

Targeted primarily at the three popular desktop implementations FreeDesktop , KDE , and GNOME , the Flatpak framework itself is written in C and works on a LGPL license. The maintenance repository can be accessed via the GitHub link here .

A few features of Flatpak that make it stand apart are mentioned below. Notice that features Flatpak shares with AppImage and Snappy are omitted here.

One of the most criticized aspects of Flatpak however is it's the sandbox feature itself. Sandboxing is how package managers such as Snappy and Flatpak implement important security features. Sandboxing essentially isolates the application from everything else in the system only allowing for user defined exchange of information from within the sandbox to outside. The flaw with the concept being that the sandbox cannot be inherently impregnable. Data has to be eventually transferred between the two domains and simple Linux commands can simply get rid of the sandbox restriction meaning that malicious applications might potentially jump out of the said sandbox.[15]

This combined with the worse than expected commitment to rolling out security updates for Flatpak has resulted in widespread criticism of the team's tall claim of providing a secure framework. The blog (named flatkill ) linked at the end of this guide in fact mentions a couple of exploits that were not addressed by the Flatpak team as soon as they should've been.[15]

For more details, I suggest you to read Flatpak official documentation .


Related read:


AppImage vs Snap vs Flatpak

The table attached below summarizes all the above findings into a concise and technical comparison of the three frameworks.

Feature AppImage Snappy Flatpak
Unique feature
Not an appstore or repository, its simply put a packaging format for software distribution. Led by Canonical (Same company as Ubuntu), features central app repository and active contribution from Canonical. Features an app store called FlatHub, however, individuals may still host packages and distribute it.
Target system Desktops and Servers. Desktops, Servers, IoT devices, Embedded devices etc. Desktops and limited function on servers.
Libraries/Dependencies Base system. Runtimes optional, Libraries and other dependencies packaged. Base system or via Plugins or can be packaged. GNOME, KDE, Freedesktop bundled or custom bundled.
Developers Community Driven led by Simon Peter. Corporate driven by Canonical Ltd. Community driven by flatpak team supported by enterprise.
Written in C. Golang, C and Python. C.
Initial release 2004. 2014. 2015.
Sandboxing Can be implemented. 3 modes – strict, classic, and devmode with varying confinement capabilities. Runs in isolation. Isolated but Uses system files to run applications by default.
Sandboxing Platform Firejail, AppArmor, Bubblewrap. AppArmor. Bubblewrap.
App Installation Not necessary. Will act as self mounted disc. Installation using snapd. Installed using flatpak client tools.
App Execution Can be run after setting executing bit. Using desktop integrated snap tools. Runs isolated with user defined resources. Needs to be executed using flatpak command if CLI is used.
User Privileges Can be run w/o root user access. Can be run w/o root user access. Selectively required.
Hosting Applications Can be hosted anywhere by anybody. Has to be hosted with Canonical servers which are proprietary. Can be hosted anywhere by anybody.
Portable Execution from non system locations Yes. No. Yes, after flatpak client is configured.
Central Repository AppImageHub. Snap Store. Flathub.
Running multiple versions of the app Possible, any number of versions simultaneously. One version of the app in one channel. Has to be separately configured for more. Yes.
Updating applications Using CLI command AppImageUpdate or via an updater tool built into the AppImage. Requires snapd installed. Supports delta updating, will automatically update. Required flatpak installed. Update Using flatpak update command.
Package sizes on disk Application remains archived. Application remains archived. Client side is uncompressed.

Here is a long tabular comparison of AppImage vs. Snap vs. Flatpak features. Please note that the comparison is made from an AppImage perspective.

Conclusion

While all three of these platforms have a lot in common with each other and aim to be platform agnostic in approach, they offer different levels of competencies in a few areas. While Snaps can run on a variety of devices including embedded ones, AppImages and Flatpaks are built with the desktop user in mind. AppImages of popular applications on the other had have superior packaging sizes and portability whereas Flatpak really shines with its forward compatibility when its used in a set it and forget it system.

If there are any flaws in this guide, please let us know in the comment section below. We will update the guide accordingly.

References:

[Jul 29, 2018] The evolution of package managers by Steve Ovens (Red Hat)

Jul 26, 2018 | opensource.com

Package managers play an important role in Linux software management. Here's how some of the leading players compare.

Join the 85,000 open source advocates who receive our giveaway alerts and article roundups.

https://opensource.com/eloqua-embedded-email-capture-block.html?offer_id=70160000000QzXNAA0

Linux adopted early the practice of maintaining a centralized location where users could find and install software. In this article, I'll discuss the history of software installation on Linux and how modern operating systems are kept up to date against the never-ending torrent of CVEs .

How was software on Linux installed before package managers?

Historically, software was provided either via FTP or mailing lists (eventually this distribution would grow to include basic websites). Only a few small files contained the instructions to create a binary (normally in a tarfile). You would untar the files, read the readme, and as long as you had GCC or some other form of C compiler, you would then typically run a ./configure script with some list of attributes, such as pathing to library files, location to create new binaries, etc. In addition, the configure process would check your system for application dependencies. If any major requirements were missing, the configure script would exit and you could not proceed with the installation until all the dependencies were met. If the configure script completed successfully, a Makefile would be created.

Once a Makefile existed, you would then proceed to run the make command (this command is provided by whichever compiler you were using). The make command has a number of options called make flags , which help optimize the resulting binaries for your system. In the earlier days of computing, this was very important because hardware struggled to keep up with modern software demands. Today, compilation options can be much more generic as most hardware is more than adequate for modern software.

Finally, after the make process had been completed, you would need to run make install (or sudo make install ) in order to actually install the software. As you can imagine, doing this for every single piece of software was time-consuming and tedious -- not to mention the fact that updating software was a complicated and potentially very involved process.

What is a package?

Packages were invented to combat this complexity. Packages collect multiple data files together into a single archive file for easier portability and storage, or simply compress files to reduce storage space. The binaries included in a package are precompiled with according to the sane defaults the developer chosen. Packages also contain metadata, such as the software's name, a description of its purpose, a version number, and a list of dependencies necessary for the software to run properly.

Several flavors of Linux have created their own package formats. Some of the most commonly used package formats include:

While packages themselves don't manage dependencies directly, they represented a huge step forward in Linux software management.

What is a software repository?

A few years ago, before the proliferation of smartphones, the idea of a software repository was difficult for many users to grasp if they were not involved in the Linux ecosystem. To this day, most Windows users still seem to be hardwired to open a web browser to search for and install new software. However, those with smartphones have gotten used to the idea of a software "store." The way smartphone users obtain software and the way package managers work are not dissimilar. While there have been several attempts at making an attractive UI for software repositories, the vast majority of Linux users still use the command line to install packages. Software repositories are a centralized listing of all of the available software for any repository the system has been configured to use. Below are some examples of searching a repository for a specifc package (note that these have been truncated for brevity):

Arch Linux with aurman

user@arch ~ $ aurman -Ss kate

extra/kate 18.04.2-2 (kde-applications kdebase)
Advanced Text Editor
aur/kate-root 18.04.0-1 (11, 1.139399)
Advanced Text Editor, patched to be able to run as root
aur/kate-git r15288.15d26a7-1 (1, 1e-06)
An advanced editor component which is used in numerous KDE applications requiring a text editing component

CentOS 7 using YUM

[user@centos ~]$ yum search kate

kate-devel.x86_64 : Development files for kate
kate-libs.x86_64 : Runtime files for kate
kate-part.x86_64 : Kate kpart plugin

Ubuntu using APT

user@ubuntu ~ $ apt search kate
Sorting... Done
Full Text Search... Done

kate/xenial 4:15.12.3-0ubuntu2 amd64
powerful text editor

kate-data/xenial,xenial 4:4.14.3-0ubuntu4 all
shared data files for Kate text editor

kate-dbg/xenial 4:15.12.3-0ubuntu2 amd64
debugging symbols for Kate

kate5-data/xenial,xenial 4:15.12.3-0ubuntu2 all
shared data files for Kate text editor

What are the most prominent package managers?

As suggested in the above output, package managers are used to interact with software repositories. The following is a brief overview of some of the most prominent package managers.

RPM-based package managers

Updating RPM-based systems, particularly those based on Red Hat technologies, has a very interesting and detailed history. In fact, the current versions of yum (for enterprise distributions) and DNF (for community) combine several open source projects to provide their current functionality.

Initially, Red Hat used a package manager called RPM (Red Hat Package Manager), which is still in use today. However, its primary use is to install RPMs, which you have locally, not to search software repositories. The package manager named up2date was created to inform users of updates to packages and enable them to search remote repositories and easily install dependencies. While it served its purpose, some community members felt that up2date had some significant shortcomings.

The current incantation of yum came from several different community efforts. Yellowdog Updater (YUP) was developed in 1999-2001 by folks at Terra Soft Solutions as a back-end engine for a graphical installer of Yellow Dog Linux . Duke University liked the idea of YUP and decided to improve upon it. They created Yellowdog Updater, Modified (yum) which was eventually adapted to help manage the university's Red Hat Linux systems. Yum grew in popularity, and by 2005 it was estimated to be used by more than half of the Linux market. Today, almost every distribution of Linux that uses RPMs uses yum for package management (with a few notable exceptions).

Working with yum

In order for yum to download and install packages out of an internet repository, files must be located in /etc/yum.repos.d/ and they must have the extension .repo . Here is an example repo file:

[local_base]
name=Base CentOS (local)
baseurl=http://7-repo.apps.home.local/yum-repo/7/
enabled=1
gpgcheck=0

This is for one of my local repositories, which explains why the GPG check is off. If this check was on, each package would need to be signed with a cryptographic key and a corresponding key would need to be imported into the system receiving the updates. Because I maintain this repository myself, I trust the packages and do not bother signing them.

Once a repository file is in place, you can start installing packages from the remote repository. The most basic command is yum update , which will update every package currently installed. This does not require a specific step to refresh the information about repositories; this is done automatically. A sample of the command is shown below:

[user@centos ~]$ sudo yum update
Loaded plugins: fastestmirror, product-id, search-disabled-repos, subscription-manager
local_base | 3.6 kB 00:00:00
local_epel | 2.9 kB 00:00:00
local_rpm_forge | 1.9 kB 00:00:00
local_updates | 3.4 kB 00:00:00
spideroak-one-stable | 2.9 kB 00:00:00
zfs | 2.9 kB 00:00:00
(1/6): local_base/group_gz | 166 kB 00:00:00
(2/6): local_updates/primary_db | 2.7 MB 00:00:00
(3/6): local_base/primary_db | 5.9 MB 00:00:00
(4/6): spideroak-one-stable/primary_db | 12 kB 00:00:00
(5/6): local_epel/primary_db | 6.3 MB 00:00:00
(6/6): zfs/x86_64/primary_db | 78 kB 00:00:00
local_rpm_forge/primary_db | 125 kB 00:00:00
Determining fastest mirrors
Resolving Dependencies
--> Running transaction check

If you are sure you want yum to execute any command without stopping for input, you can put the -y flag in the command, such as yum update -y .

Installing a new package is just as easy. First, search for the name of the package with yum search :

[user@centos ~]$ yum search kate

artwiz-aleczapka-kates-fonts.noarch : Kates font in Artwiz family
ghc-highlighting-kate-devel.x86_64 : Haskell highlighting-kate library development files
kate-devel.i686 : Development files for kate
kate-devel.x86_64 : Development files for kate
kate-libs.i686 : Runtime files for kate
kate-libs.x86_64 : Runtime files for kate
kate-part.i686 : Kate kpart plugin

Once you have the name of the package, you can simply install the package with sudo yum install kate-devel -y . If you installed a package you no longer need, you can remove it with sudo yum remove kate-devel -y . By default, yum will remove the package plus its dependencies.

There may be times when you do not know the name of the package, but you know the name of the utility. For example, suppose you are looking for the utility updatedb , which creates/updates the database used by the locate command. Attempting to install updatedb returns the following results:

[user@centos ~]$ sudo yum install updatedb
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
No package updatedb available.
Error: Nothing to do

You can find out what package the utility comes from by running:

[user@centos ~]$ yum whatprovides *updatedb
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile

bacula-director-5.2.13-23.1.el7.x86_64 : Bacula Director files
Repo : local_base
Matched from:
Filename : /usr/share/doc/bacula-director-5.2.13/updatedb

mlocate-0.26-8.el7.x86_64 : An utility for finding files by name
Repo : local_base
Matched from:
Filename : /usr/bin/updatedb

The reason I have used an asterisk * in front of the command is because yum whatprovides uses the path to the file in order to make a match. Since I was not sure where the file was located, I used an asterisk to indicate any path.

There are, of course, many more options available to yum. I encourage you to view the man page for yum for additional options.

Dandified Yum (DNF) is a newer iteration on yum. Introduced in Fedora 18, it has not yet been adopted in the enterprise distributions, and as such is predominantly used in Fedora (and derivatives). Its usage is almost exactly the same as that of yum, but it was built to address poor performance, undocumented APIs, slow/broken dependency resolution, and occasional high memory usage. DNF is meant as a drop-in replacement for yum, and therefore I won't repeat the commands -- wherever you would use yum , simply substitute dnf .

Working with Zypper

Zypper is another package manager meant to help manage RPMs. This package manager is most commonly associated with SUSE (and openSUSE ) but has also seen adoption by MeeGo , Sailfish OS , and Tizen . It was originally introduced in 2006 and has been iterated upon ever since. There is not a whole lot to say other than Zypper is used as the back end for the system administration tool YaST and some users find it to be faster than yum.

Zypper's usage is very similar to that of yum. To search for, update, install or remove a package, simply use the following:

zypper search kate
zypper update
zypper install kate
zypper remove kate

Some major differences come into play in how repositories are added to the system with zypper . Unlike the package managers discussed above, zypper adds repositories using the package manager itself. The most common way is via a URL, but zypper also supports importing from repo files.

suse:~ # zypper addrepo http://download.videolan.org/pub/vlc/SuSE/15.0 vlc
Adding repository 'vlc' [done]
Repository 'vlc' successfully added

Enabled : Yes
Autorefresh : No
GPG Check : Yes
URI : http://download.videolan.org/pub/vlc/SuSE/15.0
Priority : 99

You remove repositories in a similar manner:

suse:~ # zypper removerepo vlc
Removing repository 'vlc' ...................................[done]
Repository 'vlc' has been removed.

Use the zypper repos command to see what the status of repositories are on your system:

suse:~ # zypper repos
Repository priorities are without effect. All enabled repositories share the same priority.

# | Alias | Name | Enabled | GPG Check | Refresh
---+---------------------------+-----------------------------------------+---------+-----------+--------
1 | repo-debug | openSUSE-Leap-15.0-Debug | No | ---- | ----
2 | repo-debug-non-oss | openSUSE-Leap-15.0-Debug-Non-Oss | No | ---- | ----
3 | repo-debug-update | openSUSE-Leap-15.0-Update-Debug | No | ---- | ----
4 | repo-debug-update-non-oss | openSUSE-Leap-15.0-Update-Debug-Non-Oss | No | ---- | ----
5 | repo-non-oss | openSUSE-Leap-15.0-Non-Oss | Yes | ( p) Yes | Yes
6 | repo-oss | openSUSE-Leap-15.0-Oss | Yes | ( p) Yes | Yes

zypper even has a similar ability to determine what package name contains files or binaries. Unlike YUM, it uses a hyphen in the command (although this method of searching is deprecated):

localhost:~ # zypper what-provides kate
Command 'what-provides' is replaced by 'search --provides --match-exact'.
See 'help search' for all available options.
Loading repository data...
Reading installed packages...

S | Name | Summary | Type
---+------+----------------------+------------
i+ | Kate | Advanced Text Editor | application
i | kate | Advanced Text Editor | package

As with YUM and DNF, Zypper has a much richer feature set than covered here. Please consult with the official documentation for more in-depth information.

Debian-based package managers

One of the oldest Linux distributions currently maintained, Debian's system is very similar to RPM-based systems. They use .deb packages, which can be managed by a tool called dpkg . dpkg is very similar to rpm in that it was designed to manage packages that are available locally. It does no dependency resolution (although it does dependency checking), and has no reliable way to interact with remote repositories. In order to improve the user experience and ease of use, the Debian project commissioned a project called Deity . This codename was eventually abandoned and changed to Advanced Package Tool (APT) .

Released as test builds in 1998 (before making an appearance in Debian 2.1 in 1999), many users consider APT one of the defining features of Debian-based systems. It makes use of repositories in a similar fashion to RPM-based systems, but instead of individual .repo files that yum uses, apt has historically used /etc/apt/sources.list to manage repositories. More recently, it also ingests files from /etc/apt/sources.d/ . Following the examples in the RPM-based package managers, to accomplish the same thing on Debian-based distributions you have a few options. You can edit/create the files manually in the aforementioned locations from the terminal, or in some cases, you can use a UI front end (such as Software & Updates provided by Ubuntu et al.). To provide the same treatment to all distributions, I will cover only the command-line options. To add a repository without directly editing a file, you can do something like this:

user@ubuntu:~$ sudo apt-add-repository "deb http://APT.spideroak.com/ubuntu-spideroak-hardy/ release restricted"

This will create a spideroakone.list file in /etc/apt/sources.list.d . Obviously, these lines change depending on the repository being added. If you are adding a Personal Package Archive (PPA), you can do this:

user@ubuntu:~$ sudo apt-add-repository ppa:gnome-desktop

NOTE: Debian does not support PPAs natively.

After a repository has been added, Debian-based systems need to be made aware that there is a new location to search for packages. This is done via the apt-get update command:

user@ubuntu:~$ sudo apt-get update
Get:1 http://security.ubuntu.com/ubuntu xenial-security InRelease [107 kB]
Hit:2 http://APT.spideroak.com/ubuntu-spideroak-hardy release InRelease
Hit:3 http://ca.archive.ubuntu.com/ubuntu xenial InRelease
Get:4 http://ca.archive.ubuntu.com/ubuntu xenial-updates InRelease [109 kB]
Get:5 http://security.ubuntu.com/ubuntu xenial-security/main amd64 Packages [517 kB]
Get:6 http://security.ubuntu.com/ubuntu xenial-security/main i386 Packages [455 kB]
Get:7 http://security.ubuntu.com/ubuntu xenial-security/main Translation-en [221 kB]
...

Fetched 6,399 kB in 3s (2,017 kB/s)
Reading package lists... Done

Now that the new repository is added and updated, you can search for a package using the apt-cache command:

user@ubuntu:~$ apt-cache search kate
aterm-ml - Afterstep XVT - a VT102 emulator for the X window system
frescobaldi - Qt4 LilyPond sheet music editor
gitit - Wiki engine backed by a git or darcs filestore
jedit - Plugin-based editor for programmers
kate - powerful text editor
kate-data - shared data files for Kate text editor
kate-dbg - debugging symbols for Kate
katepart - embeddable text editor component

To install kate , simply run the corresponding install command:

user@ubuntu:~$ sudo apt-get install kate

To remove a package, use apt-get remove :

user@ubuntu:~$ sudo apt-get remove kate

When it comes to package discovery, APT does not provide any functionality that is similar to yum whatprovides . There are a few ways to get this information if you are trying to find where a specific file on disk has come from.

Using dpkg

user@ubuntu:~$ dpkg -S /bin/ls
coreutils: /bin/ls

Using apt-file

user@ubuntu:~$ sudo apt-get install apt-file -y

user@ubuntu:~$ sudo apt-file update

user@ubuntu:~$ apt-file search kate

The problem with apt-file search is that it, unlike yum whatprovides , it is overly verbose unless you know the exact path, and it automatically adds a wildcard search so that you end up with results for anything with the word kate in it:

kate: /usr/bin/kate
kate: /usr/lib/x86_64-linux-gnu/qt5/plugins/ktexteditor/katebacktracebrowserplugin.so
kate: /usr/lib/x86_64-linux-gnu/qt5/plugins/ktexteditor/katebuildplugin.so
kate: /usr/lib/x86_64-linux-gnu/qt5/plugins/ktexteditor/katecloseexceptplugin.so
kate: /usr/lib/x86_64-linux-gnu/qt5/plugins/ktexteditor/katectagsplugin.so

Most of these examples have used apt-get . Note that most of the current tutorials for Ubuntu specifically have taken to simply using apt . The single apt command was designed to implement only the most commonly used commands in the APT arsenal. Since functionality is split between apt-get , apt-cache , and other commands, apt looks to unify these into a single command. It also adds some niceties such as colorization, progress bars, and other odds and ends. Most of the commands noted above can be replaced with apt , but not all Debian-based distributions currently receiving security patches support using apt by default, so you may need to install additional packages.

Arch-based package managers

Arch Linux uses a package manager called pacman . Unlike .deb or .rpm files, pacman uses a more traditional tarball with the LZMA2 compression ( .tar.xz ). This enables Arch Linux packages to be much smaller than other forms of compressed archives (such as gzip ). Initially released in 2002, pacman has been steadily iterated and improved. One of the major benefits of pacman is that it supports the Arch Build System , a system for building packages from source. The build system ingests a file called a PKGBUILD, which contains metadata (such as version numbers, revisions, dependencies, etc.) as well as a shell script with the required flags for compiling a package conforming to the Arch Linux requirements. The resulting binaries are then packaged into the aforementioned .tar.xz file for consumption by pacman.

This system led to the creation of the Arch User Repository (AUR) which is a community-driven repository containing PKGBUILD files and supporting patches or scripts. This allows for a virtually endless amount of software to be available in Arch. The obvious advantage of this system is that if a user (or maintainer) wishes to make software available to the public, they do not have to go through official channels to get it accepted in the main repositories. The downside is that it relies on community curation similar to Docker Hub , Canonical's Snap packages, or other similar mechanisms. There are numerous AUR-specific package managers that can be used to download, compile, and install from the PKGBUILD files in the AUR (we will look at this later).

Working with pacman and official repositories

Arch's main package manager, pacman, uses flags instead of command words like yum and apt . For example, to search for a package, you would use pacman -Ss . As with most commands on Linux, you can find both a manpage and inline help. Most of the commands for pacman use the sync (-S) flag. For example:

user@arch ~ $ pacman -Ss kate

extra/kate 18.04.2-2 (kde-applications kdebase)
Advanced Text Editor
extra/libkate 0.4.1-6 [installed]
A karaoke and text codec for embedding in ogg
extra/libtiger 0.3.4-5 [installed]
A rendering library for Kate streams using Pango and Cairo
extra/ttf-cheapskate 2.0-12
TTFonts collection from dustimo.com
community/haskell-cheapskate 0.1.1-100
Experimental markdown processor.

Arch also uses repositories similar to other package managers. In the output above, search results are prefixed with the repository they are found in ( extra/ and community/ in this case). Similar to both Red Hat and Debian-based systems, Arch relies on the user to add the repository information into a specific file. The location for these repositories is /etc/pacman.conf . The example below is fairly close to a stock system. I have enabled the [multilib] repository for Steam support:

[options]
Architecture = auto

Color
CheckSpace

SigLevel = Required DatabaseOptional
LocalFileSigLevel = Optional

[core]
Include = /etc/pacman.d/mirrorlist

[extra]
Include = /etc/pacman.d/mirrorlist

[community]
Include = /etc/pacman.d/mirrorlist

[multilib]
Include = /etc/pacman.d/mirrorlist

It is possible to specify a specific URL in pacman.conf . This functionality can be used to make sure all packages come from a specific point in time. If, for example, a package has a bug that affects you severely and it has several dependencies, you can roll back to a specific point in time by adding a specific URL into your pacman.conf and then running the commands to downgrade the system:

[core]
Server=https://archive.archlinux.org/repos/2017/12/22/$repo/os/$arch

Like Debian-based systems, Arch does not update its local repository information until you tell it to do so. You can refresh the package database by issuing the following command:

user@arch ~ $ sudo pacman -Sy

:: Synchronizing package databases...
core 130.2 KiB 851K/s 00:00 [##########################################################] 100%
extra 1645.3 KiB 2.69M/s 00:01 [##########################################################] 100%
community 4.5 MiB 2.27M/s 00:02 [##########################################################] 100%
multilib is up to date

As you can see in the above output, pacman thinks that the multilib package database is up to date. You can force a refresh if you think this is incorrect by running pacman -Syy . If you want to update your entire system (excluding packages installed from the AUR), you can run pacman -Syu :

user@arch ~ $ sudo pacman -Syu

:: Synchronizing package databases...
core is up to date
extra is up to date
community is up to date
multilib is up to date
:: Starting full system upgrade...
resolving dependencies...
looking for conflicting packages...

Packages (45) ceph-13.2.0-2 ceph-libs-13.2.0-2 debootstrap-1.0.105-1 guile-2.2.4-1 harfbuzz-1.8.2-1 harfbuzz-icu-1.8.2-1 haskell-aeson-1.3.1.1-20
haskell-attoparsec-0.13.2.2-24 haskell-tagged-0.8.6-1 imagemagick-7.0.8.4-1 lib32-harfbuzz-1.8.2-1 lib32-libgusb-0.3.0-1 lib32-systemd-239.0-1
libgit2-1:0.27.2-1 libinput-1.11.2-1 libmagick-7.0.8.4-1 libmagick6-6.9.10.4-1 libopenshot-0.2.0-1 libopenshot-audio-0.1.6-1 libosinfo-1.2.0-1
libxfce4util-4.13.2-1 minetest-0.4.17.1-1 minetest-common-0.4.17.1-1 mlt-6.10.0-1 mlt-python-bindings-6.10.0-1 ndctl-61.1-1 netctl-1.17-1
nodejs-10.6.0-1

Total Download Size: 2.66 MiB
Total Installed Size: 879.15 MiB
Net Upgrade Size: -365.27 MiB

:: Proceed with installation? [Y/n]

In the scenario mentioned earlier regarding downgrading a system, you can force a downgrade by issuing pacman -Syyuu . It is important to note that this should not be undertaken lightly. This should not cause a problem in most cases; however, there is a chance that downgrading of a package or several packages will cause a cascading failure and leave your system in an inconsistent state. USE WITH CAUTION!

To install a package, simply use pacman -S kate :

user@arch ~ $ sudo pacman -S kate

resolving dependencies...
looking for conflicting packages...

Packages (7) editorconfig-core-c-0.12.2-1 kactivities-5.47.0-1 kparts-5.47.0-1 ktexteditor-5.47.0-2 syntax-highlighting-5.47.0-1 threadweaver-5.47.0-1
kate-18.04.2-2

Total Download Size: 10.94 MiB
Total Installed Size: 38.91 MiB

:: Proceed with installation? [Y/n]

To remove a package, you can run pacman -R kate . This removes only the package and not its dependencies:

user@arch ~ $ sudo pacman -S kate

checking dependencies...

Packages (1) kate-18.04.2-2

Total Removed Size: 20.30 MiB

:: Do you want to remove these packages? [Y/n]

If you want to remove the dependencies that are not required by other packages, you can run pacman -Rs:

user@arch ~ $ sudo pacman -Rs kate

checking dependencies...

Packages (7) editorconfig-core-c-0.12.2-1 kactivities-5.47.0-1 kparts-5.47.0-1 ktexteditor-5.47.0-2 syntax-highlighting-5.47.0-1 threadweaver-5.47.0-1
kate-18.04.2-2

Total Removed Size: 38.91 MiB

:: Do you want to remove these packages? [Y/n]

Pacman, in my opinion, offers the most succinct way of searching for the name of a package for a given utility. As shown above, yum and apt both rely on pathing in order to find useful results. Pacman makes some intelligent guesses as to which package you are most likely looking for:

user@arch ~ $ sudo pacman -Fs updatedb
core/mlocate 0.26.git.20170220-1
usr/bin/updatedb

user@arch ~ $ sudo pacman -Fs kate
extra/kate 18.04.2-2
usr/bin/kate

Working with the AUR

There are several popular AUR package manager helpers. Of these, yaourt and pacaur are fairly prolific. However, both projects are listed as discontinued or problematic on the Arch Wiki . For that reason, I will discuss aurman . It works almost exactly like pacman, except it searches the AUR and includes some helpful, albeit potentially dangerous, options. Installing a package from the AUR will initiate use of the package maintainer's build scripts. You will be prompted several times for permission to continue (I have truncated the output for brevity):

aurman -S telegram-desktop-bin
~~ initializing aurman...
~~ the following packages are neither in known repos nor in the aur
...
~~ calculating solutions...

:: The following 1 package(s) are getting updated:
aur/telegram-desktop-bin 1.3.0-1 -> 1.3.9-1

?? Do you want to continue? Y/n: Y

~~ looking for new pkgbuilds and fetching them...
Cloning into 'telegram-desktop-bin'...

remote: Counting objects: 301, done.
remote: Compressing objects: 100% (152/152), done.
remote: Total 301 (delta 161), reused 286 (delta 147)
Receiving objects: 100% (301/301), 76.17 KiB | 639.00 KiB/s, done.
Resolving deltas: 100% (161/161), done.
?? Do you want to see the changes of telegram-desktop-bin? N/y: N

[sudo] password for user:

...
==> Leaving fakeroot environment.
==> Finished making: telegram-desktop-bin 1.3.9-1 (Thu 05 Jul 2018 11:22:02 AM EDT)
==> Cleaning up...
loading packages...
resolving dependencies...
looking for conflicting packages...

Packages (1) telegram-desktop-bin-1.3.9-1

Total Installed Size: 88.81 MiB
Net Upgrade Size: 5.33 MiB

:: Proceed with installation? [Y/n]

Sometimes you will be prompted for more input, depending on the complexity of the package you are installing. To avoid this tedium, aurman allows you to pass both the --noconfirm and --noedit options. This is equivalent to saying "accept all of the defaults, and trust that the package maintainers scripts will not be malicious." USE THIS OPTION WITH EXTREME CAUTION! While these options are unlikely to break your system on their own, you should never blindly accept someone else's scripts.

Conclusion

This article, of course, only scratches the surface of what package managers can do. There are also many other package managers available that I could not cover in this space. Some distributions, such as Ubuntu or Elementary OS, have gone to great lengths to provide a graphical approach to package management.

If you are interested in some of the more advanced functions of package managers, please post your questions or comments below and I would be glad to write a follow-up article.

Appendix # search for packages
yum search <package>
dnf search <package>
zypper search <package>
apt-cache search <package>
apt search <package>
pacman -Ss <package>

# install packages
yum install <package>
dnf install <package>
zypper install <package>
apt-get install <package>
apt install <package>
pacman -Ss <package>

# update package database, not required by yum, dnf and zypper
apt-get update
apt update
pacman -Sy

# update all system packages
yum update
dnf update
zypper update
apt-get upgrade
apt upgrade
pacman -Su

# remove an installed package
yum remove <package>
dnf remove <package>
apt-get remove <package>
apt remove <package>
pacman -R <package>
pacman -Rs <package>

# search for the package name containing specific file or folder
yum whatprovides *<binary>
dnf whatprovides *<binary>
zypper what-provides <binary>
zypper search --provides <binary>
apt-file search <binary>
pacman -Sf <binary>

Topics Linux About the author Steve Ovens - Steve is a dedicated IT professional and Linux advocate. Prior to joining Red Hat, he spent several years in financial, automotive, and movie industries. Steve currently works for Red Hat as an OpenShift consultant and has certifications ranging from the RHCA (in DevOps), to Ansible, to Containerized Applications and more. He spends a lot of time discussing technology and writing tutorials on various technical subjects with friends, family, and anyone who is interested in listening. More about me

Software and configuration management made easy with RPM by Christian Stankowic

September 3, 2013 | servicesblog.redhat.com

If you're maintaining multiple Red Hat Enterprise Linux systems (or equivalent offsets like CentOS or Scientific Linux) your administration work with the particular hosts will gain in a routine. Because even the best administrator might forget something it would be advantageously to have a central software and configuration management solution. Chef and Puppet are two very mighty and popular management tools for this application. Depending on your system landscape and needs these tools might also be oversized though – Red Hat Package Manager (RPM) can emerge as a functional alternative in this case.

It is often forgotten that RPM can be used for sharing own software and configurations as well. If you're not managing huge system landscapes with uncontrolled growth of software and want to have a easy-to-use solution, you might want to have a look at RPM.

I'm myself using RPM to maintain my whole Red Hat Enterprise Linux system landscape – this article will show you how easy RPM can be used to simplify system management.


Platform

The core of this scenario is a web-service which can be implemented on a dedicated host or on a pre-existing server (e.g. web server) as well. This web-service offers RPM packages for downloading and doesn't even need to be a RHEL or CentOS system because the server only serves the RPM files (and ideally doesn't create them).

RPM packages are created and replicated to the web server using SSH and Rsync on dedicated RHEL or CentOS systems depending on the distribution releases you want to maintain (e.g. RHEL 5 and 6). A YUM repository is created of the RPM packages collection preliminary using createrepo. The YUM repository can be used by additional servers and other clients and consists of multiple sub-directories that are named after the supported processor architectures. After the repository had been configured on the client it can be used for downloading and installing additional software packages. If you only have to maintain RPM packages for one distribution release you can scale down your test environment.

In this case a YUM repository for the Red Hat Enterprise Linux releases 5 and 6 is created.

Web server file structure

The YUM repository directory (myrepo in this case) consists of multiple sub-directories containing the software packages per supported distribution release and processor architecture. The names of these folders are very important – the name has to be the same like the value of the appropriate YUM variable $releasever (discussed later!).

A table of popular RPM-based Linux distributions:

$releasever Explanation
5Server RHEL 5
6Server RHEL 6
5Workstation RHED 5
6Workstation RHED 6
5 / 5.1 / 5.2 / … CentOS / Scientific Linux 5
6 / 6.1 / 5.2 / … CentOS / Scientific Linux 6
17 / 18 / … Fedora 17 / 18 / …

Example: If you want to serve software packages for the Red Hat Enterprise Linux releases 5 and 6 you'll have to create two sub-directories: 5Server and 6Server.

This implies the following directory structure:

myrepo/
       /5Server
            .../repodata
            .../noarch
                      ...
            .../i686
                    ...
            .../x86_64
                      ...
       /6Server
               (see above)
               ...

The appropriate main directories are created on the web server – the sub-directories and further contents are copied to the machine using SSH / Rsync later:

# mkdir -p /var/www/html/myrepo/{5,6}Server

Preparation

Before RPM packages can be created and served to other hosts using a YUM repository several development tools need to be installed:

# yum install rpm-build createrepo rpmdevtools

I suggest to create the RPM packages on dedicated hosts or virtual machines and copy the packages to the web server using SSH and Rsync afterwards. The web server should never be used as development environment additionally, due to security reasons. Especially if you want to serve packages for multiple distribution releases (RHEL5, RHEL6) you will definitely need appropriate test environments.

The web server host needs to be prepared for serving the data (if not done yet) – e.g. for a EL system:

# yum install httpd
# chkconfig httpd on
# system-config-firewall-tui
# service httpd start

Due to security reasons, a dedicated service user for creating the packages is created on the development machines. RPM packages should never be created under the user context of root! Afterwards the needed directory structures are created using rpmdev-setuptree (this command doesn't exist under EL5):

# useradd su-rpmdev
# passwd su-rpmdev
# su - su-rpmdev
$ rpmdev-setuptree
$ ln -s /usr/src/redhat ~su-rpmdev/rpmbuild    #symb. link under EL5

If you're using EL5 you'll find the needed structures below /usr/src/redhat – the directory permissions need to be set for the created user su-rpmdev. In the new created folder rpmbuild (respectively below /usr/src/redhat) consists of the following sub-directories:

SOURCES and SPECS are the most important directories – most of the time the RPM farmer is moving around there. 😉

Example 1: configuration files

The most administrators will customize the standard configuration of a Enterprise Linux systems to fit their needs. Some popular examples of customizable configuration files are:

As a matter of principle, creating RPM packages is a complex topic which is only raised roughly in this article. If you want to go deeper with this topic you might want to have a look at the Fedora wiki and documentation – there are plenty useful information:

In thie case a NTP configuration shall be packaged in a RPM file and rolled out on all hosts in the company. First of all, a specfile is created for the future RPM package:

$ cd ~su-rpmdev/rpmbuild/SPECS
$ rpmdev-newspec mycompany-ntp
Skeleton specfile (minimal) has been created to "mycompany-ntp.spec".

All rpmdev tools doesn't exist under EL5 so that you'll have to create the specfile on your own!

If you're on EL6, the previous command created a skeleton of a RPM specfile – this file is edited using an editor now:

$ vim mycompany-ntp.spec
Name:           mycompany-ntp
Version:
Release:        1%{?dist}
Summary:

Group:
License:
URL:
Source0:

BuildRequires:
Requires:

%description

%prep
%setup -q

%build
%configure
make %{?_smp_mflags}

%install
rm -rf $RPM_BUILD_ROOT
make install DESTDIR=$RPM_BUILD_ROOT

%clean
rm -rf $RPM_BUILD_ROOT

%files
%defattr(-,root,root,-)
%doc

%changelog

Beside meta information about the application, additional scripts for compiling and creating the package are included. The particular meta variables are largely self-explanatory – some explanations:

Some of the additional script or macro segments:

To be honest – it's not hard to lose track in the beginning. I suggest to have a look at finished RPM specfiles – often you'll learn some "tricks" by having a look at other's work.

There are two ways to have a look at finished RPM specfiles. Some additional repositories are serving their specfiles over SVN or GIT. As an example, Repoforge has a public GIT mirror for this: [click me!]

Another possibility is to include the optional source code channels of additional repositories – like EPEL – and download the source code packages:

# vi /etc/yum.repos.d/epel.repo
...
[epel-source]
...
enabled=1

ESC ZZ
# yum install yum-utils
# yumdownloader --source nrpe

The RPM packages can be adapted using cpio – another more comfortable way is to use Midnight Commander to examine the package. The RPM package includes a CPIO archive named CONTENTS.cpio – the specfile is stored there:

To build a preferably "clean" package it is important to create a source code archive – even if you only want to share configuration files. It is also possible to create those files directly in the install macro of the specfile – but especially if you want to share multiple or long configuration files you'll lose track . In this case an archive containing the NTP configuration is created:

$ mkdir ~/rpmbuild/SOURCES/mycompany-ntp-1.0
$ cd ~/rpmbuild/SOURCES/mycompany-ntp-1.0
$ vi ntp.conf
driftfile /var/lib/ntp/drift
server localserver.loc

ESC ZZ
$ cd ..
$ tar cf mycompany-ntp-1.0.tar.gz mycompany-ntp-1.0/*

Afterwards the RPM specfile is modified – my version looks like this:

$ cd ../SPECS
$ cat mycompany-ntp.spec
Name:           mycompany-ntp
Version:        1.0
Release:        1%{?dist}
Summary:        MyCompany customized NTP configuration

Group:          System Environment/Daemons
License:        GPL
Source0:        %name-%version.tar.gz

Requires:       ntp

%description
This package includes MyCompany customized NTP configuration files.
Feel free to delete this package if received outside the MyCompany network.

%prep
%setup -q

%build

%install
rm -rf $RPM_BUILD_ROOT
install -m 0755 -d %{buildroot}%{_sysconfdir}/mycompany
install -m 0644 ntp.conf %{buildroot}%{_sysconfdir}/mycompany/ntp.conf

%clean
rm -rf $RPM_BUILD_ROOT

%files
%config(noreplace) %{_sysconfdir}/mycompany/ntp.conf

I'm sure you notices that the modified NTP configuration file isn't stored at its accurate place (/etc/ntp.conf) – it is rather saved in an alternative directory (/etc/mycompany/ntp.conf). The reason for this is that the former configuration file (which is provided by the ntp package) can be replaced because of the noreplace flag:

#code quote of the ntp RPM specfile
%files
%config(noreplace) %{_sysconfdir}/ntp.conf

This package stores its configuration file in an alternative directory which can't be overwritten by other RPM packages.

You'll have to help yourself by using a "trigger trick" that saves the former configuration and creates a symbolic link to the new configuration after the installation. After the uninstallation of the package this step is rolled back. For implement this you'll have to add the following macros to your RPM specfile:

%triggerin -- mycompany-ntp
if [ ! -h /etc/ntp.conf -o ! "`readlink /etc/ntp.conf`" = "/etc/mycompany/ntp.conf" ] ; then
        if [ -e /etc/ntp.conf ] ; then
                mv -f /etc/ntp.conf /etc/ntp.conf.orig
        fi
        ln -s /etc/mycompany/ntp.conf /etc/ntp.conf
fi

%triggerun -- mycompany-ntp
if [ $1 -eq 0 -a $2 -gt 0 -a -e /etc/ntp.conf.orig ] ; then
        mv -f /etc/ntp.conf.orig /etc/ntp.conf
fi

%triggerpostun -- mycompany-ntp
if [ $2 -eq 0 ]; then
        rm -f /etc/ntp.conf.rpmsave /etc/ntp.conf.orig
fi
if [ -e /etc/ntp.conf.rpmnew ] ; then
        mv /etc/ntp.conf.rpnnew /etc/ntp.conf.orig
fi

%postun
if [ -e /etc/ntp.conf.orig -a -h /etc/ntp.conf -a ! -e "`readlink /etc/ntp.conf`" ] ; then
        mv -f /etc/ntp.conf.orig /etc/ntp.conf
fi

Simplified summarization of the triggers functions:

  1. Installation: if the former configuration file exists ".orig" is appended to the file name and a symbolic link to the new configuration file is created
  2. Deinstallation of the customized NTP configuration: if the former configuration file still exists the file name is reset
  3. After uninstalling the customized NTP configuration: remaining additional or newly added NTP configuration files are deleted
  4. After uninstalling: resetting the file name of the former NTP configuration file

I abdicated the URL and BuildRequires tags in my specfile because there are no websites or special compiling dependencies for a customized NTP configuration. 😉

Example 2: Meta packages

There are plenty of applications and configuration that are part of a senseful customized system installation – to name some practical examples: sudo configuration, GNU Screen (of course!), and customized application profiles.

To avoid doing the application installation manually everytime, meta packages can be built to simplify the process. These packages don't have their own files – they only have dependencies to other packages.

Because of this, RPM meta packages aren't assigned to special processor architectures (x86_64, i686, s390,…) – an additional specification "BuildArch noarch" is added in the specfile.

Another practical example: a meta package for installing NTP including the customized configuration and telnet for checking the daemon's function:

$ cd SOURCES
$ mkdir mycompany-ntp-full-1.0
$ tar cvfz mycompany-ntp-full-1.0.tar.gz mycompany-ntp-full-1.0
$ cd ../SPECS
$ cat mycompany-ntp-full.spec
Name:           mycompany-ntp-full
Version:        1.0
Release:        1%{?dist}
Summary:        MyCompany customized NTP configuration and netstat utility

Group:          System Environment/Daemons
License:        GPL
Source0:        %name-%version.tar.gz

BuildArch:      noarch
Requires:       ntp mycompany-ntp net-tools

%description
This package includes MyCompany customized NTP configuration files.
Feel free to delete this package if received outside the MyCompany network.

%prep
%setup -q

%build

%install

%clean
rm -rf $RPM_BUILD_ROOT

%files

Using rpm you can list the package's dependencies:

$ rpmbuild -bb mycompany-ntp-full.spec
$ rpm --query -Rp ../RPMS/noarch/mycompany-ntp-full-1.0-1.el6.noarch.rpm
ntp
mycompany-ntp
net-tools
rpmlib(PayloadFilesHavePrefix) <= 4.0-1
rpmlib(CompressedFileNames) <= 3.0.4-1

Package dependencies can very depending on the distribution release. In this example between RHEL5 and 6 – the packages providing the telnet command are different here:

rhel5 # rpm -qf $(which telnet)
krb5-workstation-1.6.1-70.el5_9.2
rhel6 # rpm-qf $(which telnet)
net-tools-1.60-110.el6_2.x86_64

You might want to consider this in the specfile:

Requires:       ntp mycompany-ntp
%{?el5:Requires: krb5-workstation}
%{?el6:Requires: net-tools}

The first dependeny line is significant for all releases, the following lines are considered under RHEL5 or RHEL6.

You can also define particular versions in combination with the Requires and Conflicts tags – for example, if you want to reference a myapp package which is at least version 1.1. One of the following lines can be used:

Requires:        myapp >= 1.1
Conflicts:       myapp < 1.1

If you want to reference a special version of a package there are also two possibilities – choose one:

Requires:        myapp = 1.1
Conflicts:       myapp < 1.1 myapp > 1.1

It's a kind of philosophical question which of the two possibilites is used – like the question if the glass is half-full or half-empty. Either a package is excluded or referenced explicitely. 😉

Further information regarding RPM dependencies can be found on the official RPM website: [click me!]

Let's go back to the former motivation of this meta package: as an alternative you can also define package groups in your own YUM repository. If you have already worked with the YUM commands grouplist, groupinstall and groupremove, you might know this logical grouping of software packages. You can find an interesting article about this in the YUM wiki: [click me!]

Package and repository creation

Okay – we have a RPM specfile now, what's next? RPM packages are creating using the rpmbuild utility. This tool has a plenty of swithces and arguments – as an example you can also create source code packages or packages for additional processor architectures.

Important parameters:

Parameter Explanation
-ba Creates a binary and source code package
-bb Creates a binary package
-bp Extracting and patching (if necessary) of the source code
-bs Creates a source code package
–target=noarch Creates a platform independent package
–target=i686 …a 32-bit package
–target=x86_64 …a 64-bit package

Some examples:

# Creates a binary and source code package of myapp
$ rpmbuild -ba myapp.spec
# Creates a 32-bit binary package of myapp
$ rpmbuild -bb --target=i686 myapp.spec

Afterwards you'll find a RPM package below RPMS depending on your processor architecture (noarch, i686 or x86_64). If you're a proud owner of a IBM System Z machine you might want to have a look below s390 or s390z. 😉

$ ls RPMS/*/*.rpm
RPMS/i386/mycompany-ntp-1.0-1.el6.i386.rpm

This RPM package could now be installed using YUM:

# yum localinstall --nogpgcheck mycompany-ntp-1.0-1.el6.i386.rpm

Synchronization and automation

After creating the RPM packages on the particular test machines (e.g. RHEL6 and RHEL5) the packages need to be copied to the web server. I suggest using SSH and Rsync for a synchronization between the test machines, the main test machine and the web server.

If you don't want to do this manually every time you can automate this using a small script:

1.Synchronization between the EL5 machine and the main test machine:

$ ln -s /usr/src/redhat /home/su-rpmdev/rpmbuild
$ vi /home/su-rpmdev/export_repo.sh
#!/bin/sh
rsync -avz --delete /home/su-rpmdev/rpmbuild/RPMS/ /opt/myrepo
createrepo --database /opt/myrepo/
rsync -avz --delete -e ssh /opt/myrepo/ su-rpmdev@MAIN:/opt/myrepo/5Server

ESC ZZ
$ chmod +x /home/su-rpmdev/export_repo.sh
$ ./home/su-rpmdev/export_repo.sh

The first rsync command copied all RPM packages of all processor architectures below /opt/myrepo – if a RPM package is deleted in the source, it is also deleted below /opt/myrepo. createrepo created a SQLite database for the YUM repository (myrepo) below /opt/myrepo. The second rsync command copies the local YUM repository to the main test machine (MAIN).

2.Synchronization between the main test machine (EL6) and the web server:

$ vi /home/su-rpmdev/export_repo.sh
#!/bin/sh
rsync -avz --delete /home/su-rpmdev/rpmbuild/RPMS/ /opt/myrepo/6Server
createrepo --database /opt/myrepo/6Server
rsync -avz --delete -e ssh /opt/myrepo/ su-rpmdev@WEB:/var/www/html/myrepo

ESC ZZ
$ chmod +x /home/su-rpmdev/export_repo.sh
$ ./home/su-rpmdev/export_repo.sh

The first rsync command copies all (EL6) RPM packages below /opt/myrepo/6Server. After that createrepo creates a SQLite-Datenbank for the EL6 repository. The second rsync command copies the whole repository (including the other EL5 repository) to the web server (WEB).

Usage and test

To use the new YUM repository on other hosts, an appropriate YUM configuration needs to be created. In this file the repository URL and other parameters like package signing are defined. The syntax looks a bit like good-old Windows .ini files:

# vi /etc/yum.repos.d/myrepo.repo
[myrepo]
name=mycompany packages for EL
baseurl=http://server01/$releasever
enabled=1
gppgcheck=0

ESC ZZ

You might see the variable $releasever – it was mentioned in the table above. This variable is replaced by another value depending on your distribution release – in this case by 5Server or 6Server. These directories had been filled with the appropriate RPM packages from the test machines.

After that, all available packages of the repository can be listed:

# yum --disablerepo='*' --enablerepo='myrepo' makecache
# yum --disablerepo='*' --enablerepo='myrepo' list available
...
mycompany-ntp                      1.0-1                      myrepo

If you have multiple repository web servers (e.g. because of big setups for processing the amount of requests or compensate failures) you can assign a mirror list:

# vi /etc/yum.repos.d/myrepo.repo
[myrepo]
...
#baseurl=...
mirrorlist=myrepo.mirror

ESC ZZ
# vi /etc/yum.repos.d/myrepo.mirror
http://server01/$releasever
http://server02/$releasever
http://server03/$releasever

For every download YUM uses one of these servers – beginning with the first one. If this server fails or doesn't have the file YUM will select the next server.

By the way – these configuration files could be shared using a RPM package, too. If this is done, you only need to install a RPM package to access the YUM repository zugreifen. This is how access to Fedora's Extra Packages For Enterprise Linux (EPEL) is provided: [click me!]

This package could look like this:

# vi SPECS/myrepo-release.spec
Name:           myrepo-release
Version:        1.0
Release:        1%{?dist}
Summary:        mycompany Packages for Enterprise Linux repository configuration

Group:          System Environment/Base
BuildArch:      noarch
License:        GPL
URL:            http://www.mycompany.com
Source0:        myrepo-release-%{version}.tar.gz
BuildRoot:      %{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)

%description
This package contains the mycompany customized Packages for Enterprise Linux repository.

%prep
%setup -q

%build

%install
install -m 0755 -d %{buildroot}%{_sysconfdir}/yum.repos.d/
install -m 0755 myrepo.repo %{buildroot}%{_sysconfdir}/yum.repos.d/myrepo.repo
install -m 0755 myrepo.mirror %{buildroot}%{_sysconfdir}/yum.repos.d/myrepo.mirror

%clean
rm -rf $RPM_BUILD_ROOT

%files
%config(noreplace) %{_sysconfdir}/yum.repos.d/myrepo.repo
%config(noreplace) %{_sysconfdir}/yum.repos.d/myrepo.mirror

%changelog
* Sat Jun 29 2013 FirstName LastName  - 1.0-1
- initial release

ESC ZZ
# tar tvfz SOURCES/myrepo-release-1.0.tar.gz
-rw-r--r-- su-rpmdev/su-rpmdev 94 2013-06-28 18:12 myrepo-release-1.0/myrepo.mirror
-rw-r--r-- su-rpmdev/su-rpmdev 189 2013-06-28 18:09 myrepo-release-1.0/myrepo.repo

# tar xvfz SOURCES/myrepo-release-1.0.tar.gz -C SOURCES/
# cat SOURCES/myrepo-release-1.0/myrepo.mirror
http://server01/$releasever
http://server02/$releasever
http://server03/$releasever
# cat SOURCES/myrepo-release-1.0/myrepo.repo
[myrepo]
name=mycompany packages for EL
#baseurl=http://server01/$releasever
mirrorlist=/etc/yum.repos.d/myrepo.mirror
enabled=1
gppgcheck=0

After the RPM specfile had been created the package can be created and distributed easily. Finally, you only have to install the RPM package to use the YUM repository:

# rpmbuild -bb SPECS/myrepo-release.spec
# scp RPMS/noarch/myrepo-release-1.0-1.rpm root@host:/root
root@host # yum localinstall --nogpgcheck myrepo-release*.rpm
root@host # yum repolist
repoid            reponame
...
myrepo            mycompany packages for EL

Et voilΰ! 🙂

Perspective / Additional ideas

Of course there is a lot that can be optimized. To name some of these things:

To manage a plenty of systems you don't need a "egg-laying, milk-bearing woolly sow" – RPM is a mighty tool which can also be used for software and configuration management. If you're engaged with Red Hat Enterprise Linux, you will often into a situation where you have to automate something quickly. And that's where RPM can also help you to reach your goal quickly.

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License

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