Managing Software Packages with yum in RHEL7/CENTOS7

The default utility used to manage software packages on Red Hat Enterprise Linux and CENTOS is yum, which stands for Yellowdog update manager. Yum is designed to work with repositories, which are online depots of available software packages.

yum
YUM(yellowdog Updater Modified)

 

While installing Red Hat Enterprise Linux, it asks you to register with Red Hat Network (RHN). From RHN, different repositories are provided. After registering with RHN, you can install software packages that are verified by Red Hat automati- cally. If you are using CentOS, you get access to the CentOS repositories. If you choose to install Red Hat Enterprise Linux without a registration key, however, it cannot get in touch with the RHN repositories, and you end up with no repositories at all. In that case, you have to be able to specify yourself which repository you want to use.Note that repositories are specific to an operating system.

To tell your server which repository to use, you need to create a file with a name that ends in .repo. In that file you need the following contents:

[label] The .repo file can contain different repositories, each section starting with a label that identifies the specific repository.
 name= Use this to specify the name of the repository you want to use.
 baseurl= Contains the URL that points to the specific repository location.
In the repository files that are provided by default, you may find several repositories in one file, . This is useful to group reposi tories that belong together in one file, and is often done in repository files that are provided as a default. If you are creating repository files yourself, you are free to create separate files for each repository.

Working with yum search

To install packages with yum, you first need to know the exact name of the package. The yum search command can help you with that. When you use yum search, it first gets in touch with the online repositories (which might take a minute), after which it downloads the most recent repository metadata to the local machine. Then, yum search looks in the package name and description for the string you have been looking for.

[[email protected] Desktop]# yum search nmap
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
 * base: mirror.nbrc.ac.in
 * epel: ftp.jaist.ac.jp
 * extras: mirror.nbrc.ac.in
 * nux-dextop: mirror.li.nux.ro
 * updates: mirror.nbrc.ac.in
============================== N/S matched: nmap ===============================
nmap-frontend.noarch : The GTK+ front end for nmap
nmap-ncat.x86_64 : Nmap's Netcat replacement
nmap.x86_64 : Network exploration tool and security scanner

 Name and summary matches only, use "search all" for everything.
yum info

Once you search for a package using yum search, you can use ‘yum info package’ to view additional information about the package.

[[email protected] Desktop]# yum info nmap
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
 * base: mirror.nbrc.ac.in
 * epel: ftp.riken.jp
 * extras: mirror.nbrc.ac.in
 * nux-dextop: mirror.li.nux.ro
 * updates: mirror.nbrc.ac.in
Available Packages
Name        : nmap
Arch        : x86_64
Epoch       : 2
Version     : 6.40
Release     : 7.el7
Size        : 4.0 M
Repo        : base/7/x86_64
Summary     : Network exploration tool and security scanner
URL         : http://nmap.org/
License     : GPLv2 and LGPLv2+ and GPLv2+ and BSD
Description : Nmap is a utility for network exploration or security auditing.
            : It supports ping scanning (determine which hosts are up), many
            : port scanning techniques (determine what services the hosts are
            : offering), and TCP/IP fingerprinting (remote host operating system
            : identification). Nmap also offers flexible target and port
            : specification, decoy scanning, determination of TCP sequence
            : predictability characteristics, reverse-identd scanning, and more.
            : In addition to the classic command-line nmap executable, the Nmap
            : suite includes a flexible data transfer, redirection, and
            : debugging tool (netcat utility ncat), a utility for comparing scan
            : results (ndiff), and a packet generation and response analysis
            : tool (nping).

 

Installing Software with yum

we can install packages by using yum install package-name command.

# yum install -y nmap

[[email protected] ~]# yum install nmap
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
 * base: mirror.nbrc.ac.in
 * epel: ftp.jaist.ac.jp
 * extras: mirror.nbrc.ac.in
 * nux-dextop: mirror.li.nux.ro
 * updates: mirrors.vinahost.vn
Resolving Dependencies
--> Running transaction check
---> Package nmap.x86_64 2:6.40-7.el7 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

==============================================================================================================================================
 Package                          Arch                               Version                                   Repository                        Size
======================================================================================================================================================
Installing:
 nmap                             x86_64                             2:6.40-7.el7                              base                             4.0 M

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

Total download size: 4.0 M
Installed size: 16 M
Is this ok [y/d/N]: y
Downloading packages:
nmap-6.40-7.el7.x86_64.rpm                                                                                                     | 4.0 MB  00:00:31     
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Installing : 2:nmap-6.40-7.el7.x86_64                                                                                                           1/1 
  Verifying  : 2:nmap-6.40-7.el7.x86_64                                                                                                           1/1 

Installed:
  nmap.x86_64 2:6.40-7.el7                                                                                                                            

Complete!

By default ‘yum install’, will prompt you to accept or decline before installing the packages. If you want yum to install automatically without prompting, use -y option.

We could also update the nmap package. Just change the command from install to update

# yum update -y nmap

Uninstall a package using yum remove

[[email protected] ~]# yum remove nmap
Loaded plugins: fastestmirror, langpacks
Resolving Dependencies
--> Running transaction check
---> Package nmap.x86_64 2:6.40-7.el7 will be erased
--> Finished Dependency Resolution

Dependencies Resolved

======================================================================================================================================================
 Package                          Arch                               Version                                  Repository                         Size
======================================================================================================================================================
Removing:
 nmap                             x86_64                             2:6.40-7.el7                             @base                              16 M

Transaction Summary
======================================================================================================================================================
Remove  1 Package

Installed size: 16 M
Is this ok [y/N]: y
Downloading packages:
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Erasing    : 2:nmap-6.40-7.el7.x86_64                                                                                                           1/1 
  Verifying  : 2:nmap-6.40-7.el7.x86_64                                                                                                           1/1 

Removed:
  nmap.x86_64 2:6.40-7.el7                                                                                                                            

Complete!

By using Yum list command you can list out the available packages in yum Repositories

#yum list

[[email protected] Desktop]# yum list |grep less
java-1.7.0-openjdk-headless.x86_64         1:1.7.0.91-2.6.2.3.el7     @anaconda 
java-1.8.0-openjdk-headless.x86_64         1:1.8.0.65-3.b17.el7       @anaconda 
less.x86_64                                458-9.el7                  @anaconda 
java-1.7.0-openjdk-headless.x86_64         1:1.7.0.95-2.6.4.0.el7_2   updates   
java-1.8.0-openjdk-headless.x86_64         1:1.8.0.71-2.b15.el7_2     updates   
java-1.8.0-openjdk-headless-debug.x86_64   1:1.8.0.71-2.b15.el7_2     updates   
lesstif.x86_64                             0.95.2-8.el7               epel      
lesstif-clients.x86_64                     0.95.2-8.el7               epel      
lesstif-devel.x86_64                       0.95.2-8.el7               epel      
lesstif-mwm.x86_64                         0.95.2-8.el7               epel      
libreoffice-headless.x86_64                1:4.3.7.2-5.el7_2.1        updates   
nodejs-less.noarch                         1.7.0-2.el7                epel      
php-lessphp.noarch                         0.5.0-2.el7                epel      
python-blessings.noarch                    1.5-3.el7                  epel      
python-lesscpy.noarch                      0.9j-4.el7                 epel      
wireless-tools.x86_64                      1:29-13.el7                epel      
wireless-tools-debuginfo.x86_64            1:29-9.1.el7.nux           nux-dextop
wireless-tools-devel.x86_64                1:29-13.el7                epel

If you want to see which packages are installed on your server,instead  you can use the yum list installed command.

#yum list installed

[[email protected] Desktop]# yum list installed |grep less
java-1.7.0-openjdk-headless.x86_64    1:1.7.0.91-2.6.2.3.el7         @anaconda  
java-1.8.0-openjdk-headless.x86_64    1:1.8.0.65-3.b17.el7           @anaconda  
less.x86_64                           458-9.el7                      @anaconda  

The yum list command can also prove useful when used with the name of a specific package as its argument.

While managing specific services on a Linux machine, you often need several different  packages. If, for instance,while configuring your server as a web server, you need to install additional packages like PHP as well in many cases.Instead of searching and installing all the individual packages that belongs to a specific function, you can simply install the group, which will install all the packages that belongs to the group.

[[email protected] ~]# yum group list


Available Groups:
   CIFS file server
   Compatibility Libraries
   Console Internet Tools
   Desktop
   Desktop Platform
   Desktop Platform Development
   Development Tools
   Eclipse
   Educational Software
   Electronic Lab
   FCoE Storage Client
   Fedora Packager
   General Purpose Desktop
   Graphical Administration Tools
   Haskell
   Legacy UNIX Compatibility
   Messaging Client Support
   Messaging Server Support
   Milkymist
   MySQL Database client
   MySQL Database server
   NFS file server
   Network Storage Server
   SNMP Support
   Scientific Support
   Security Tools
   Server Platform
   Server Platform Development
   Smart Card Support
   Storage Availability Tools
   System Administration Tools
   System Management
   TeX support
   TurboGears application framework
   Virtualization
   Web-Based Enterprise Management
   Xfce
   iSCSI Storage Client
Done
# yum groupinstall "<group name>"

we can  install specific software group, by using  groupinstall option.

If you’ve already installed a software group using yum groupinstall, and would like to upgrade it to the latest version, use ‘yum groupupdate’ and we can remove it by using yum groupremove

Yum repolist

All yum commands goes against one or more yum repositories. To view all the yum repositories that are configured in your system, do ‘yum repolist’ as shown below.

The following will display only the enabled repositories.

[[email protected] Desktop]# yum repolist
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
 * base: mirror.nbrc.ac.in
 * epel: ftp.jaist.ac.jp
 * extras: mirror.nbrc.ac.in
 * nux-dextop: mirror.li.nux.ro
 * updates: mirror.nbrc.ac.in
repo id                repo name                                         status
!adobe-linux-x86_64    Adobe Systems Incorporated                            2
!base/7/x86_64         CentOS-7 - Base                                   9,007
!bsrtech               bsrtech                                           1,164
*!epel/x86_64          Extra Packages for Enterprise Linux 7 - x86_64    9,627
!extras/7/x86_64       CentOS-7 - Extras                                   226
!nux-dextop/x86_64     Nux.Ro RPMs for general desktop use               2,360
!updates/7/x86_64      CentOS-7 - Updates                                  919
repolist: 23,305

Yum provides

Use ‘yum provides’ if you like to know which package a particular file belongs to. For example, if you like to know the name of the package that has the /etc/httpd/conf/httpd.conf file, do the following.

[[email protected] Desktop]# yum provides /etc/httpd/conf/httpd.conf
Loaded plugins: fastestmirror, langpacks

httpd-2.4.6-40.el7.centos.x86_64 : Apache HTTP Server
Repo        : base
Matched from:
Filename    : /etc/httpd/conf/httpd.conf



httpd-2.4.6-40.el7.centos.x86_64 : Apache HTTP Server
Repo        : @anaconda
Matched from:
Filename    : /etc/httpd/conf/httpd.conf

 

Yum clean

The “yum clean all” command will not only remove cached packages, but also any headers. i do it occasionally to totally flush out everything in case there are obsolete headers – which can also take up space.

yum clean packages
Eliminate any cached packages from the system. Note that pack-
ages are not automatically deleted after they are downloaded.

yum clean headers
Eliminate all of the files which yum uses to determine the
remote availability of packages. Using this option will force
yum to download all the headers the next time it is run.

yum clean all
Runs yum clean packages and yum clean headers as above.”

[[email protected] Desktop]# yum clean
Loaded plugins: fastestmirror, langpacks
Error: clean requires an option: headers, packages, metadata, dbcache, plugins
, expire-cache, rpmdb, all
[[email protected] Desktop]# yum clean all
Loaded plugins: fastestmirror, langpacks
Cleaning repos: adobe-linux-x86_64 base bsrtech epel extras nux-dextop updates
Cleaning up everything
Cleaning up list of fastest mirrors

 

Yum History

While working with yum, all actions are logged to the /var/log/yum.log file. You can use the yum history command to get an overview of all actions that have been issued.

[[email protected] ~]# yum history
Loaded plugins: fastestmirror, langpacks
ID     | Login user               | Date and time    | Action(s)      | Altered
-------------------------------------------------------------------------------
    10 | root <root>              | 2016-03-16 15:32 | Erase          |    1   
     9 | root <root>              | 2016-03-16 15:23 | Install        |    1   
     8 | root <root>              | 2016-03-16 14:52 | Install        |    1   
     7 | root <root>              | 2016-03-14 13:49 | Install        |    1   
     6 | root <root>              | 2016-03-14 13:48 | Install        |   37   
     5 | root <root>              | 2016-03-14 13:25 | Install        |    1   
     4 | root <root>              | 2016-03-14 13:25 | Update         |    1   
     3 | root <root>              | 2016-03-14 13:17 | Install        |    1  
     2 | root <root>              | 2016-03-14 12:47 | Install        |    1  
     1 | System <unset>           | 2016-03-14 11:17 | Install        | 1939   
history list

From the history file, it is possible to undo specific actions; use yum history undo followed by the number of the specific action(mentioned as ID in above output) you want to undo.

On your system, two package databases are maintained:
The yum database and
  The rpm database.
When you are installing packages through yum, the yum database is  updated first, after which the updated information is synchronized to the RPM database. If you install packages using the rpm command, the update is written to the rpm database only and will not be updated to the yum database, which is an important reason not to use the rpm command anymore to install software packages.

 

 

 

NO COMMENTS