On previous post we have described about yum install, update, upgrade, remove, reinstall packages. The basic yum commands are below,

1. yum repolist

'repolist' you will see some numbers, those are the number of packges in the repository. repo id, repo name and status.

# yum repolist

repo id                                      repo name                                               status
!base/7/x86_64                               CentOS-7 - Base                                         8,652
*!epel/x86_64                                Extra Packages for Enterprise Linux 7 - x86_64          7,760
!extras/7/x86_64                             CentOS-7 - Extras                                       84
!mysql-connectors-community/x86_64           MySQL Connectors Community                              14
!mysql-tools-community/x86_64                MySQL Tools Community                                   17
!mysql56-community/x86_64                    MySQL 5.6 Community Server                              139
repolist: 17,536

2. yum search:

 yum search command is very easy to search related packages on 'yum search package-name'

3. yum-config-manager

'yum-config-manager' command for  add, enable, and disable a repository.

To add repository,

yum-config-manager  --add-repo repository_url
# yum-config-manager --add-repo http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm

The below command disable  and enable pgdg94 repository (pgsql)

How to enable specific repo.
# yum-config-manager --enable pgdg94

How to disable  specific repo.
# yum-config-manager --disable pgdg94

4. yum list:

List installed packages only

The yum-config-manager is telling yum to hide all the packages being with the string "kernel". Can see the kernel packages,
# yum list kernel

# yum list installed

List available packages only
# yum list available

Displaying all installed and available packages from the repository and system.
# yum list all

to Get information about specific package details use 'info'
# yum info vsftpd

Available Packages
Name        : vsftpd
Arch        : x86_64
Version     : 2.2.2
Release     : 13.el6_6.1
Size        : 151 k
Repo        : cloudlinux-x86_64-server-6
Summary     : Very Secure Ftp Daemon
License     : GPLv2 with exceptions
Description : vsftpd is a Very Secure FTP daemon. It was written completely from
            : scratch.

4. yum provides:

Find packages that provide queried files, the below command shows packages containing samba server.
# yum provides samba

5. yum clean :
# yum clean vsftpd

To delete package saved in cache
# yum clean all

Clean out all packages and meta data from cache

6. Help :
# yum help

# man yum

7. To Find  yum location: 
# whereis yum
yum: /usr/bin/yum /etc/yum /etc/yum.conf /usr/share/man/man8/yum.8