Consider this process has (2) main parts. The first part you need only do one time, for the first time you update flash player. The second part you do each time a new update is released. Plugin updates from Adobe are security patches only.
If you have already added partner repositories then you can skip Part 1 and go directly to Part 2. Always run 'apt-get update' before installation.
Part 1: First Time Pre-Update Configuration
As "root" or using sudo (place the command 'sudo' before all commands below if not already root...
What flash plugin packages are already installed?
apt-cache pkgnames|grep -i flash
You might see "flashplugin-installer" in the list. flashplugin-installer installs the 32-bit version of Flash and a related compatibility library which may be slower and less stable, so it’s recommended to install the adobe-flashplugin package from canonial partners repository.
To enable the partners repositor open the sources.list file
vi /etc/apt/sources.list
Add the partner repositories by removing the # in front of the following lines
deb http://archive.canonical.com/ubuntu precise partner
Part 2: Subsequent Regular Update
In this example we are using Ubuntu Precise (Precise Pangolin). If you're using another version simply replace "precise" with the correct string. Now Synchronize the package index files. This is necessary each time before checking for an update to the flash plugin to make sure the index is current.
apt-get update
Now update to the latest version of flash
apt-get install adobe-flashplugin
Additional Information
Adobe Flash Player 11.2 was released in 2012 which Adobe announced would be the last native version for Linux. This isn't a problem for Google Chrome users as the plugin is built into the browser. Firefox users are left out. However, Adobe does seem to release occasional "security" updates for 11.2 such as an update in late 2014 (11.2.202.425) which corrected a known exploit (Adobe Flash is full of security holes.) Firefox users would have seen a message similar to:
Flash Player Plugin on Linux 11.2.202.424 and lower (click-to-play) has been blocked for your protection.
HTML5 is an alternative to Adobe Flash that web developers are encouraged to use rather than creating Flash objects.
Flash is under the Restricted Formats in Ubuntu. Because of Adobe's anti-competitive and anti-open standards license restrictions on Flash, the people at Ubuntu say they cannot include Flash automatically. This is why "partners" repository has to be enabled. They also want people to consider using one of the open-source Flash player alternatives that will render Flash objects.
- Lightspark is available from the project's Launchpad page: https://launchpad.net/lightspark.
- Gnash and Swfdec are available as Ubuntu packages from the Universe repository.
On Some Systems
Edubantu system older distribution kernel 3.11.0-26-generic / Ubuntu 12.04.5 LTS
sudo apt-get install flashplugin-installer