INFORMATICS

Repository installation

# dnf install https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm
# dnf install https://rpms.remirepo.net/enterprise/remi-release-8.rpm



EPEL stand for Extra Packages for Enterprise Linux.
EPEL repository is a Fedora Special Interest Group that creates, maintains, and manages a high quality set of additional packages for Enterprise Linux, 
including, but not limited to, Red Hat Enterprise Linux (RHEL), CentOS and Scientific Linux (SL), Oracle Enterprise Linux(OEL).

Extra Packages for Enterprise Linux (EPEL) - (See http://fedoraproject.org/wiki/EPEL) provides rebuilds of Fedora packages for EL6 and EL7. Packages should not replace base, although there have been issues around point releases in the past. You can install EPEL by running yum --enablerepo=extras install epel-release. The epel-release package is included in the CentOS Extras repository that is enabled by default. Support available on Freenode in #epel, on mailing lists, and its issue tracker. If you are willing to help test EPEL updates before they are pushed to stable, you can enable the epel-testing repository on your development/testing servers. Enabling epel-testing on production systems is not a good idea.

Remi repository is a yum repository maintained by a French dude – Remi Collet. This post describe the basic steps to prepare and install the additional 
CentOS packages with EPEL and Remi Repository into CentOS 6.

Remi Repository - (See http://rpms.remirepo.net/) Remi Collet maintains a large collection of RPMS, including latest versions of PHP etc. 
He's also got an FAQ at http://blog.remirepo.net/pages/English-FAQ . 
Note that this is a collection of repos, and using the -safe series will ensure that nothing from the base CentOS Linux distro is overwritten or replaced. 
However, be aware that this repo does not play nicely with other third party repos - for example, 
Remi's packages contain Obsoletes: lines for packages from both IUS and Webtatic repos and thus will automatically replace them with the .remi version. 
This may not be the desired behaviour and you should be careful with enabling this repo for that reason.

About 'enabled' and 'disabled' repository configuration files

Please read man 5 yum.conf, particularly the discussion of enabled=0 versus enabled=1 . A line containing one of these options is recommended for each repository in each .conf file in the  /etc/yum.repos.d/  directory. This allows the administrator to more clearly specify whether a repository is or is not used for packages. After any edits of these files, in order to clear any cached information, and to make sure the changes are immediately recognized, as root run:

# yum clean all 



After modifying the repository file with new entries, proceed and clear the DNF / YUM cache as shown.

# dnf clean all
OR
# yum clean all

To confirm that the system will get packages from the locally defined repositories, run the command:

# dnf repolist
OR
# yum repolist