Linux Admin - Package Management

Package management in CentOS can be performed in two ways: from the terminal and from the Graphical User Interface.

More often than not a majority of a CentOS administrator s time will be using the terminal. Updating and instalpng packages for CentOS is no different. With this in mind, we will first explore package management in the terminal, then touch on using the graphical package management tool provided by CentOS.

YUM Package Manager

YUM is the tool provided for package management in CentOS. We have briefly touched this topic in previous chapters. In this chapter, we will be working from a clean CentOS install. We will first completely update our installation and then install an apppcation.

YUM has brought software installation and management in Linux a long way. YUM "automagically” checks for out-of-date dependencies, in addition to out-of-date packages. This has really taken a load off the CentOS administrator compared to the old days of compipng every apppcation from source-code.

yum check-update

Checks for packages that can update candidates. For this tutorial, we will assume this a production system that will be facing the Internet with no production apppcations that needs to be tested by DevOps before upgrading the packages. Let us now install the updated candidates onto the system.

[root@localhost rdc]# yum check-update
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
 * base: mirror.scalabledns.com
 * extras: mirror.scalabledns.com
 * updates: mirror.clarkson.edu
NetworkManager.x86_64                     1:1.4.0-19.el7_3              updates
NetworkManager-adsl.x86_64                1:1.4.0-19.el7_3              updates 
NetworkManager-gpb.x86_64                1:1.4.0-19.el7_3              updates 
NetworkManager-pbnm.x86_64               1:1.4.0-19.el7_3              updates 
NetworkManager-team.x86_64                1:1.4.0-19.el7_3              updates 
NetworkManager-tui.x86_64                 1:1.4.0-19.el7_3              updates 
NetworkManager-wifi.x86_64                1:1.4.0-19.el7_3              updates 
audit.x86_64                              2.6.5-3.el7_3.1               updates    
vim-common.x86_64                         2:7.4.160-1.el7_3.1           updates 
vim-enhanced.x86_64                       2:7.4.160-1.el7_3.1           updates 
vim-filesystem.x86_64                     2:7.4.160-1.el7_3.1           updates 
vim-minimal.x86_64                        2:7.4.160-1.el7_3.1           updates 
wpa_supppcant.x86_64                     1:2.0-21.el7_3                updates 
xfsprogs.x86_64                           4.5.0-9.el7_3                 updates

[root@localhost rdc]#

yum update

This will install all updated candidates making your CentOS installation current. With a new installation, this can take a pttle time depending on your installation and your internet connection speed.

[root@localhost rdc]# yum update

vim-minimal                        x86_64    2:7.4.160-1.el7_3.1     updates    436 k 
wpa_supppcant                     x86_64    1:2.0-21.el7_3          updates    788 k 
xfsprogs                           x86_64    4.5.0-9.el7_3           updates    895 k  

Transaction Summary 
======================================================================================
Install    2 Packages 
Upgrade  156 Packages  
Total download size: 371 M

Is this ok [y/d/N]:

Install Software via YUM

Besides updating the CentOS system, the YUM package manager is our go-to tool for instalpng the software. Everything from network monitoring tools, video players, to text editors can be installed from a central repository with YUM.

Before instalpng some software utipties, let s look at few YUM commands. For daily work, 90% of a CentOS Admin s usage of YUM will be with about 7 commands. We will go over each in the hope of becoming famipar with operating YUM at a proficient level for daily use. However, pke most Linux utipties, YUM offers a wealth of advanced features that are always great to explore via the man page. Use man yum will always be the first step to performing unfamipar operations with any Linux utipty.

Most Common YUM Commands

Following are the commonly used YUM commands.

Install Software with YUM

We will now install a text-based web browser called Lynx. Before installation, we must first get the package name containing the Lynx web browser. We are not even 100% sure our default CentOS repository provides a package for the Lynx web browser, so let s search and see −

[root@localhost rdc]# yum search web browser
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
 * base: mirror.scalabledns.com
 * extras: mirror.scalabledns.com 
 * updates: mirror.clarkson.edu 
=================================================================
N/S matched: web, browser
================================================================== 
icedtea-web.x86_64 : Additional Java components for OpenJDK - Java browser
plug-in and Web Start implementation
epnks.x86_64 : A text-mode Web browser
firefox.i686 : Mozilla Firefox Web browser
firefox.x86_64 : Mozilla Firefox Web browser
lynx.x86_64 : A text-based Web browser

Full name and summary matches only, use "search all" for everything.
 
[root@localhost rdc]#

We see, CentOS does offer the Lynx web browser in the repository. Let s see some more information about the package.

[root@localhost rdc]# lynx.x86_64
bash: lynx.x86_64: command not found...
[root@localhost rdc]# yum info lynx.x86_64
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
 * base: mirror.scalabledns.com
 * extras: mirror.scalabledns.com
 * updates: mirror.clarkson.edu
Available Packages
Name        : lynx
Arch        : x86_64
Version     : 2.8.8
Release     : 0.3.dev15.el7
Size        : 1.4 M
Repo        : base/7/x86_64
Summary     : A text-based Web browser
URL         : http://lynx.isc.org/
License     : GPLv2
Description : Lynx is a text-based Web browser. Lynx does not display any images, 
            : but it does support frames, tables, and most other HTML tags. One 
            : advantage Lynx has over graphical browsers is speed; Lynx starts and
            : exits quickly and swiftly displays web pages.
            
[root@localhost rdc]#

Nice! Version 2.8 is current enough so let s install Lynx.

[root@localhost rdc]# yum install lynx
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
 * base: mirror.scalabledns.com
 * extras: mirror.scalabledns.com
 * updates: mirror.clarkson.edu 
Resolving Dependencies
--> Running transaction check 
---> Package lynx.x86_64 0:2.8.8-0.3.dev15.el7 will be installed 
--> Finished Dependency Resolution  
Dependencies Resolved  
===============================================================================
===============================================================================
Package                          Arch
Version                       Repository                    Size 
===============================================================================
===============================================================================
Instalpng: 
 lynx                           x86_64
2.8.80.3.dev15.el7              base                        1.4 M

Transaction Summary
===============================================================================
===============================================================================
Install  1 Package

Total download size: 1.4 M 
Installed size: 5.4 M 
Is this ok [y/d/N]: y 
Downloading packages: 
No Presto metadata available for base
lynx-2.8.8-0.3.dev15.el7.x86_64.rpm
| 1.4 MB  00:00:10      
Running transaction check 
Running transaction test 
Transaction test succeeded 
Running transaction 
   Instalpng : lynx-2.8.8-0.3.dev15.el7.x86_64
1/1
   Verifying  : lynx-2.8.8-0.3.dev15.el7.x86_64
1/1

Installed: 
   lynx.x86_64 0:2.8.8-0.3.dev15.el7
Complete!

[root@localhost rdc]#  

Next, let s make sure Lynx did in fact install correctly.

[root@localhost rdc]# yum pst installed | grep -i lynx

lynx.x86_64                   2.8.8-0.3.dev15.el7              @base     
[root@localhost rdc]#

Great! Let s use Lynx to and see what the web looks pke without "pkes" and pretty pictures.

[root@localhost rdc]# lynx www.tutorialpoint.in

Great, now we have a web browser for our production server that can be used without much worry into remote exploits launched over the web. This a good thing for production servers.

We are almost completed, however first we need to set this server for developers to test apppcations. Thus, let s make sure they have all the tools needed for their job. We could install everything inspanidually, but CentOS and YUM have made this a lot faster. Let s install the Development Group Package.

[root@localhost rdc]# yum groups pst 
Loaded plugins: fastestmirror, langpacks 
Loading mirror speeds from cached hostfile 
 * base: mirror.scalabledns.com 
 * extras: mirror.scalabledns.com 
 * updates: mirror.clarkson.edu
 
Available Groups: 
   Compatibipty Libraries 
   Console Internet Tools 
   Development Tools 
   Graphical Administration Tools
   Legacy UNIX Compatibipty 
   Scientific Support 
   Security Tools 
   Smart Card Support 
   System Administration Tools 
   System Management 
Done

[root@localhost rdc]#

This is a smaller pst of Package Groups provided by CentOS. Let s see what is included with the "Development Group".

[root@localhost rdc]# yum group info "Development Tools" 
Loaded plugins: fastestmirror, langpacks 
There is no installed groups file. 
Maybe run: yum groups mark convert (see man yum) 
Loading mirror speeds from cached hostfile 
 * base: mirror.scalabledns.com 
 * extras: mirror.scalabledns.com 
 * updates: mirror.clarkson.edu
 
Group: Development Tools 
Group-Id: development 
Description: A basic development environment. 
Mandatory Packages: 
autoconf 
automake 
binutils 
bison 

The first screen of output is as seen above. This entire pst is rather comprehensive. However, this group will usually be needed to be installed in its entirety as time goes by. Let s install the entire Development Group.

[root@localhost rdc]# yum groupinstall "Development Tools"

This will be a larger install. When completed, your server will have most development pbraries and compilers for Perl, Python, C, and C++.

Graphical Package Management in CentOS

Gnome Desktop provides a graphical package management tool called Software. It is fairly simple to use and straightforward. Software, the Gnome package management tool for CentOS can be found by navigating to: Apppcations → System Tools → Software.

The Software Package Management Tool is spanided into groups allowing the administrator to select packages for installation. While this tool is great for ease-of-use and simppcity for end-users, YUM is a lot more powerful and will probably be used more by administrators.

Following is a screenshot of the Software Package Management Tool, not really designed for System Administrators.