Obtain information about installed packages on CentOS and Ubuntu

CentOS / RHEL / Fedora

List all installed packages

rpm -qa

Get information about a specific package

rpm -qi <package name> 

List all files in a specific package

rpm -ql <package name> 

Combine the -a and -l options, in this exmaple we're searching for the package elasticsearch-5.5.2-1.noarch

package=$(rpm -qa | grep elasticsearch) && rpm -ql $package; 

Ubuntu

List all installed packages

dpkg-query -l

List all files in a specific package

dpkg-query -L <package name> 

Adding new RPM's to an existing yum repo

1.) Copy the rpm to the repository directory (i.e alongside all the existing rpm's)

2.) Update the repository index:

createrepo --update <path to repo> --verbose

3.) Make sure your file permissions for <path to repo>/repodata are ok (i.e. so that your http server can access the files):

chmod -R go+rx <path to repo>/repodata

(NOTE: don't forget to ensure the actual package file (the rpm) has the correct file permissions also)

4.) Clear your yum client cache:

yum clean all 

Set up a local yum repository

Install yum-utils

yum install yum-utils createrepo

Create a directory for the repo

mkdir /my_repo

Get the RPM's to put in the repo. Use reposync to download from an existing repo or download rpm's manaully.. e.g.

wget http://mirror.lihnidos.org/CentOS/6/os/i386/Packages/NetworkManager-0.8.1-43.el6.i686.rpm

Create the repository

createrepo /my_repo

Create /etc/yum.repos.d/custom.repo with the following contents

[customrepo]

name=Custom Repository
baseurl=file:////my_repo/
enabled=1
gpgcheck=0