TuxGuitar is a free, open source tablature editor, which includes basic features such as tablature editing, score editing, triplet support and the ability to import and export Guitar Pro gp3, gp4, and gp5 files. In addition, TuxGuitar can function as a basic MIDI editor using the tablature or staff interface, and as of the 1.0 release, can import and export MIDI files. TuxGuitar’s mascot and namesake is Tux, the penguin mascot of many games and programs originally designed for Linux.
To search for Tuxguitar package in ubuntu
sudo apt-cache search tux | grep guitar
And install the found package name of tuxguitar using apt-get install <package name>
..or install ir from synaptics(if you have)
(Tux Guitar Running in Arch Linux. A guitar pro file is currently opened).