Application and Package Management Guide

 

 

Goals

 

When you have completed reading this guide, you should understand how to install, remove and update or upgrade the Linux packages on your server system. Once you have gone through the different sections of the guide, you will be able to manage the packages from the backend of the system. Note: The package format and installation types are different in both the CentOS and Ubuntu systems; therefore, please kindly select the appropriate sections for review.

Package format and installation utilities in CentOS

 

In Ubuntu, the packages are in .rpm format. (Originally standing for Red Hat Package Manager, RPM now stands for RPM Package Manager.) To install a package, you can use two types of installation utilities or commands available in Ubuntu by default -- yum and rpm.

yum

Install the packages from the specified repositories under “/etc/yum.repos.d”. It is the easiest way to install a package because, during package installation, its dependencies will be automatically located and installed also. In this way, you don't have to find and install any dependencies separately.

rpm

This is the default installation utility in the CentOS system. The rpm installation utility will not find and install dependencies. This utility is used to install, update or remove specific packages given in the command.

Manage Packages in CentOS Using yum Utility

 

Installation

1)      To install a package, you can use the following command. (Unlike the rpm installation utility, you do not have to specify the full rpm name and version here.)

yum install <package name>

For example, type the following command to install vsftpd service in your system:

The vsftpd package will then be found from the specified repository. Please type “y” to start the installation.

2)      After installation, you will have to start the service. To do this, use the following command:

/etc/init.d/<service name> start

3)      You can use the “chkconfig” command to start the service up after every reboot.

 chkconfig <service name> on

4)      Now you have successfully installed the package in your system using the yum installation utility.

Update or Upgrade

1)      To update or upgrade a package, you can use the following command:

yum update <package name>

For example, if you want to upgrade your old PHP 5.1.x version to PHP 5.2.x, all you have to do is type the command below. (The --exclude option will exclude the specified package.)

(Make sure your repository includes the PHP 5.2.x version. If required, you can add the atomic repository. For that, type the command below:

wget -q -O - http://www.atomicorp.com/installers/atomic | sh )

2)      After the system finds the packages and repositories, type “yes” to start the installation.

3)      Now you have successfully updated or upgraded the package in your system.

Package Removal

(Please note that, while removing a package using yum, package dependencies will also be removed.)

1)      To remove a package, type the following command:

yum remove <package name>

For example, follow this command to remove vsftpd:

Type “y” to start the uninstall.

2)      Now you have successfully uninstalled the service from your system.

To See Package Details

1)      To list all programs installed on your system, you can use the following command:

yum list installed

 

2)      If you want to find information about a specific program, you can use the following command:

yum list installed | grep <program name >

For example, if you want to check if vsftpd is installed, or if you want to find more information about vsftpd, you can use the following command:

3)      To know if there is an update for a particular package, please give the following command:

yum list updates | grep <package name>

For example, If you want to know available updates for PHP, you can use the given command:

4)      Now you know the basic commands you can perform to get more information on a package.

Manage Packages in CentOS Using rpm Utility

Install

1)      To install a package using the rpm installation utility, use the command below. (Note that you have to specify the full package name to install using rpm.)

rpm -ivh <package name>

i or --install: To install.

v:  To display additional information.

h or --hash: To print hash marks ("#") during installation.

For example, if you want to install the package “vsftpd-2.0.5-24.el5.x86_64.rpm”, follow the given steps:

a) Go to the folder or location where you put the package. (In this case, the package is under the root home directory.)

b) Now start the installation.

(Tip: You do not have to type the full package name manually. Type the first few letters then press the “tab” button.)

c) Now you have successfully installed the package on your system.

Package Removal (Independent Package)

1)      To remove an independent package (a package that has no dependencies),you can follow the command below:

rpm -e <package name>

For example, if you want to remove vsftpd, you can follow the steps below:

a) First, get the full package name. (Unlike yum, when using rpm you have to specify the full package name.)

(“rpm -qa” will list all packages installed in your system and “| grep <service name>” will find the package name of that service.)

b) Now that you have the full package name, combine it with the “rpm -e” command to remove the package from your system.

2)      Now you have successfully removed the independent package from your system.

Package Removal (Packages That Have Dependencies)

Sometimes when you try to remove some packages using the “rpm -e” command, you will receive dependency errors.

For example, some of your PHP packages have crashed or you have installed different versions of PHP packages and you have to remove the packages to get your PHP in working condition. If your try to remove a package, you will get the following error:

1)      In this situation, if you are sure what you are doing, you can remove the package forcefully without dependencies using the following command:

rpm -e --nodeps

This will remove the package forcefully without any dependency issues.

(Note: Please do not try the above command if you are not sure about what you are doing, or if you are testing your system, because this action may crash the service and the working of associated dependencies.)

2)      Now you have successfully removed the package from your system without any dependency issues.

Package Format and Installation Utilities in Ubuntu

 

In CentOS, the packages are in .deb format. To install a package, you can use two types of installation utilities or commands available in CentOS by default -- apt-get and dpkg.

apt-get

Install the packages from the specified repositories from the file “/etc/sorcem.repos.d”. It is the easiest way to install a package because, during package installation, its dependencies will be automatically located and installed also. In this way, you don't have to find and install any dependencies separately.

 

 

dpkg

This is the default installation utility in the Ubuntu system. The dpkg installation utility will not find and install any dependencies. This utility is used to install, update or remove specific packages given in a command.

Manage Packages in Ubuntu Using apt-get Utility

Installation

1)      To install a package, you can use the following command. (Unlike the dpkg installation utility, you do not have to specify the full rpm name and version here.)

apt-get install <package name>

For example, type the following command to install zip in your system.

2)  The zip package will be found in the specified repository. Please type “y” and press enter            to start the installation.

3)  Now you have successfully installed the zip service in your system.

Reinstall

1)      If you want to reinstall a damaged package, you can use the following command:

apt-get --reinstall install <package name>