Linux Guide/Installing software
Obtaining and Installing Applications 
There are many thousands of programs available for a Linux system and for several of the major distributions many thousands of these will be available in "pre-built" (ready to run) form through the appropriate package management system.
Package Managers 
Package managers simplify the task of organizing the software installed on the system. For example, the Synaptic package manager for Debian.
On a Debian, or Debian-based system, it might be possible to install a program by simply typing a command such as:
apt-get install mtools
In this case, the Debian package manager "apt-get", will check to see if such a program as "mtools" is available, and if so, it will check whether there are any other pre-requisite programs (dependencies) required for this program to run. If there are any dependencies, the package manager will check to see if these are available and in turn whether each of these has any dependencies, and so on, thus building a list of the required software to successfully run the required program. The package manager checks to see which of these are already installed, and for those not installed, it automatically downloads and installs each one. Ubuntu Linux (which is based on Debian Linux) can use this method, or it can use the method:
sudo apt-get install "whatever"
Or, on a Red Hat-based system, such as Fedora Core, you can use the 'Redhat Package Manager' (rpm). To install something, download an rpm package, and type a command like:
rpm -ihv mtools.rpm
To upgrade a package, use:
rpm -Uhv mtools.rpm
And to search your packages to find out which version of something you've got, do something like:
rpm -qa | grep mtools
Building Programs from Source 
- Main page: Linux Guide/Building software
Sometimes, pre-built binaries are not available or suitable, and in this case it may be required to build the program from its source code. Instructions for how to do this are normally included with the program, but most programs can be compiled using the commands:
Normally you can then install it to the computer by using the following command as the root user: