Linux Lesson 03 - Installing Applications
In this lesson we learn how to install software using the graphical interface and the shell.
The History of Installing Applications
Over the years the way we install applications has changed. Many years ago we wouldn't install software, we would run it directly from from the media on which we received the application. On the Commodore 64 or Apple IIe we would run the applications from the floppy disks. We would put in the disk for Oregon Trail then run it. Once hard drives became commonplace we wanted to copy the programs from our disks to our hard drives. The hard drives were bigger and faster then floppy drives.
When we switched to hard drives we could run bigger applications easier. Before hard drives, if an application was too big to fit on one floppy you would have to stop the program and insert the next floppy. With hard drives you could copy all the data to the drive and run the application without interruption. This process of copying the program from the floppy to the hard drive became known as installing the application. Over time this process became more than just copying data. It would do other things like add the appropriate ini files, and Program Manager icons, and later, registry settings and Start Menu icons.
As time went on this idea of installing applications changed with the technology. When CD's came out you could get a program that required multiple floppy disks onto one CD. The concept was the same, copy the contents of the CD to hard drive. More recently we download the installer from the Internet and run through a wizard to install the application.
Windows 8.x introduced a new tile interface that allows for full screen, non windowed applications. You have to download these applications through the app store. This follows a trend set by mobile OS's like Apple's iOS and Google's Android that each use an app store to deliver applications.
Installing Applications in the Desktop Environment
There are many ways to install applications in Linux, but the easiest is to use the package management system that contains a list of all available applications. The package management system is similar to the app store model. You can browse an interface, find the application you want and click install. It will handle gettings all dependencies, or other programs required to run the application.
Search the store for something you want, when you find an application you want you can click on the install button.
Once the application is installed you can access it using the menu in your desktop environment, or the shell.
Installing Applications in the Shell
You can install applications from the shell as well. The apt programs will help you install applications. If you know the name of the application you can use the apt-get command to perform the install. The following command will install wireshark, sudo apt-get install wireshark. Sudo will tell the command to run as superuser, you will be prompted for a password when you run this. Apt-get is the command with the install argument followed by the name of the application, or applications we want to install. When you enter the command to install, it will scan the list of repositories and tell you what else needs to be installed. Once you answer yes it will download the needed data from the Internet and install the applications on your computer.
We can run wireshark from the shell by typing in its name. When we do this it will run wireshark and the shell will be unusable because it's busy running wireshark. We can get around this by adding the "&" character to the end of a command. This will continue to run Wireshark in the background giving you control over the shell in the foreground. The background application will still be interactive and usable.
After installing an application using the shell it still appears in the menu.
If you don't know the name of the application you can use the apt-cache command to search the local cache of applications and descriptions in your repositories. Let's say you want to find an application that will do tcp/ip fingerprinting, type in apt-cache search tcp/ip fingerprinting and it will return the results.
The search results will include the name you can use to install the application using apt-get. In this case the application's name is nmap. We can type in sudo apt-get install nmap to install this application. If we don't want nmap after installing it we can type sudo apt-get remove nmap.