Install and Update Packages

Two package formats are in common use. Red Hat, Fedora, SUSE, and several others distributions use RPM (Redhat Package Manager). Debian and Ubuntu use a seperate .deb format. The two format are functionally similar. It's easy to convert between the two package formats with a tool such as alien.

Both RPM and .deb package systems now function as dual layer. On the lowest level are the tools that install, unistall, query packages, rpm for RPM and dpkg for .deb. On the top layer these system know how to find packages on the internet, analyze inter package dependencies and upgrade all the packages on a system. In RPM system 'yum' is the main contender and debian's APT (Advance Package Tool), but APT now works equally well with both .deb and RPM packages. 

Low Level Package Management System

Debian packages have dpkg command, we can install/remove that .deb using dpkg.

#dpkg -i {package full name.deb} To install package.

#dpkg -r {package name} To remove package.

#dpkg -l {package name} To verify that the installation worked.



High Level Package Management System

Meta package management system has several goals.

  • To simplify the locating and downloading of packages.
  • To automate the process of updating or upgrading systems.
  • To facilitate the management of inter package dependencies.

The default configuartion for the package management system usually points to one or more well known web or FTP servers that are under the distribuor's control. APT is one of the most mature package management systems. It's possible to upgrade an entire system full of software with a single apt-get command.

Configuring apt-get is by editing the configuration file /etc/apt/sources.list, which tells apt-get where to get its packages. Default configuration generally looks like;

#nano /etc/apt/sources.list



#
#deb cdrom:[Debian GNU/Linux 7.1.0 _Wheezy_ - Official i386 DVD Binary-1 20130504-15:20]/ wheezy contrib main

deb http://security.debian.org/ wheezy/updates main contrib
deb-src http://security.debian.org/ wheezy/updates main contrib

# wheezy-updates, previously known as 'volatile'
# A network mirror was not selected during install. The following entries
# are provided as examples, but you should amend them as appropriate
# for your mirror of choice.
#
deb http://ftp.debian.org/debian/ wheezy-updates main contrib
#deb-src http://ftp.debian.org/debian/ wheezy-updates main contrib


If user want to download source-code, uncomment line specify deb-src. Add any new source in the above file and CTRL + O, CTRL + X. Now run the apt command and install the upgrade packages for that;


#apt-get update To refresh the apt—get's cache of package information. 
#apt-get install {package name} To install the package.

Or 
#apt-get upgrade To install the full downloaded packages.


The upgradation can done by only root user or a normal user need to give root password.





Setting up an Internal APT Server discuss in later server session.

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