Packet mgmt

dpkg

dpkg is a package manager for Debian based systems. It can install, remove, and build packages, but unlike other package management system’s it can not automatically download and install packages and their dependencies. This section covers using dpkg to manage locally installed packages:

• To list all packages installed on the system, from a terminal prompt enter:

  dpkg -l
  

• Depending on the amount of packages on your system, this can generate a large amount of output. Pipe the output through grep to see if a specific package is installed:

  dpkg -l | grep apache2
  

  Replace apache2 with any package name, part of a package name, or other regular expression.

• To list the files installed by a package, in this case the ufw package, enter:

  dpkg -L ufw
  

• If you are not sure which package installed a file, dpkg -S may be able to tell you. For example:

  dpkg -S /etc/host.conf 
  base-files: /etc/host.conf
  

  The output shows that the /etc/host.conf belongs to the base-files package.

  	Many files are automatically generated during the package install process, and even though they are on the filesystem dpkg -S may not know which package they belong to.

• You can install a local .deb file by entering:

  sudo dpkg -i zip_2.32-1_i386.deb
  

  Change zip_2.32-1_i386.deb to the actual file name of the local .deb file.

• Uninstalling a package can be accomplished by:

  sudo dpkg -r zip
  

  	Uninstalling packages using dpkg, in most cases, is NOT recommended. It is better to use a package manager that handles dependencies, to ensure that the system is in a consistent state. For example using dpkg -r you can remove the zip package, but any packages that depend on it will still be installed and may no longer function correctly.

For more dpkg options see the man page: man dpkg.

Apt-Get

The apt-get command is a powerful command-line tool used to work with Ubuntu’s Advanced Packaging Tool (APT) performing such functions as installation of new software packages, upgrade of existing software packages, updating of the package list index, and even upgrading the entire Ubuntu system.

Being a simple command-line tool, apt-get has numerous advantages over other package management tools available in Ubuntu for server administrators. Some of these advantages include ease of use over simple terminal connections (SSH) and the ability to be used in system administration scripts, which can in turn be automated by the cron scheduling utility.

Some examples of popular uses for the apt-get utility:

• Install a Package: Installation of packages using the apt-get tool is quite simple. For example, to install the network scanner nmap, type the following:

  sudo apt-get install nmap
  

• Remove a Package: Removal of a package or packages is also a straightforward and simple process. To remove the nmap package installed in the previous example, type the following:

  sudo apt-get remove nmap
  

  	Multiple Packages: You may specify multiple packages to be installed or removed, separated by spaces.

  Also, adding the –purge options to apt-get remove will remove the package configuration files as well. This may or may not be the desired effect so use with caution.

• Update the Package Index: The APT package index is essentially a database of available packages from the repositories defined in the /etc/apt/sources.list file. To update the local package index with the latest changes made in repositories, type the following:

  sudo apt-get update
  

• Upgrade Packages: Over time, updated versions of packages currently installed on your computer may become available from the package repositories (for example security updates). To upgrade your system, first update your package index as outlined above, and then type:

  sudo apt-get upgrade
  

  For information on upgrading to a new Ubuntu release see the section called “Upgrading”.

Actions of the apt-get command, such as installation and removal of packages, are logged in the /var/log/dpkg.log log file.

For further information about the use of APT, read the comprehensive Debian APT User Manual or type:

apt-get help








Aptitude




Aptitude is a menu-driven,  text-based front-end to the Advanced Packaging  Tool (APT) system. Many of the common package management functions,  such as installation, removal, and upgrade, are performed in Aptitude with single-key commands,  which are typically lowercase letters.
 
Aptitude is best suited for  use in a non-graphical terminal environment to ensure proper functioning of the  command keys. You may start Aptitude as a normal user with the  following command at a terminal prompt:

sudo aptitude

When Aptitude starts, you  will see a menu bar at the top of the screen and two panes below the menu bar.  The top pane contains package categories, such as New  Packages and Not Installed Packages. The  bottom pane contains information related to the packages and package categories.
Using Aptitude for package  management is relatively straightforward, and the user interface makes common  tasks simple to perform. The following are examples of common package management  functions as performed in Aptitude:


Install Packages: To install a  package, locate the package via the Not Installed Packages package category, for  example, by using the keyboard arrow keys and the ENTER key, and highlight the package you  wish to install. After highlighting the package you wish to install, press the  + key, and the package entry should  turn green, indicating it has been marked for  installation. Now press g to be  presented with a summary of package actions. Press g again, and you will be prompted to become  root to complete the installation. Press ENTER which will result in a Password:  prompt. Enter your user password to become root. Finally, press g once more and you'll be prompted to  download the package. Press ENTER on  the Continue prompt, and downloading and installation  of the package will commence.
Remove Packages: To remove a  package, locate the package via the Installed Packages package category, for  example, by using the keyboard arrow keys and the ENTER key, and highlight the package you  wish to remove. After highlighting the package you wish to install, press the  - key, and the package entry should  turn pink, indicating it has been marked for removal.  Now press g to be presented with a  summary of package actions. Press g again, and you will be prompted to become root to complete the installation.  Press ENTER which will result in a  Password: prompt. Enter your user password to become root. Finally, press g once more, and you'll be prompted to  download the package. Press ENTER on  the Continue prompt, and removal of the package will  commence.
Update Package Index: To update the  package index, simply press the u key  and you will be prompted to become root to complete the update. Press ENTER which will result in a Password:  prompt. Enter your user password to become root. Updating of the package index  will commence. Press ENTER on the OK  prompt when the download dialog is presented to complete the process.
Upgrade Packages: To upgrade  packages, perform the update of the package index as detailed above, and then  press the U key to mark all packages  with updates. Now press g whereby  you'll be presented with a summary of package actions. Press g again, and you will be prompted to become  root to complete the installation. Press ENTER which will result in a Password:  prompt. Enter your user password to become root. Finally, press g once more, and you'll be prompted to  download the packages. Press ENTER on  the Continue prompt, and upgrade of the packages will  commence.


The first column of information displayed in the package list in the top  pane, when actually viewing packages lists the current state of the package, and  uses the following key to describe the state of the package:


i: Installed package
c: Package not installed, but  package configuration remains on system
p: Purged from system
v: Virtual package
B: Broken package
u: Unpacked files, but package not  yet configured
C: Half-configured - Configuration  failed and requires fix
H: Half-installed - Removal failed  and requires fix


To exit Aptitude, simply press the q key and confirm you wish to exit. Many  other functions are available from the Aptitude menu by pressing the F10 key.