clens is a Linux port of Thomas Niemann's PTLens for Windows. You can find PTLens at http://www.epaperpress.com/ptlens/
Unlike PTLens, clens is a command line program.

In order to correct lens distortions in your images you will need lens calibration data. See the README file in the data directory for further information on where to get lens calibration data.

You will also need a stitcher program. The stitcher program is what actually performs the image warping to remove lens distortions. clens creates script files that the stitcher program reads and then calls the stitcher program itself. The script file that clens produces is compatable with two different stitcher programs that I know of. One is PTStitcher, the other is nona. You must obtain one of these programs as well. PTStitcher is part of the "Panorama Tools" toolset and nona is part of "hugin". And finally, both of these use the Pano12 library which must be installed on your computer.
Lens Profiles are aviable at /usr/share/clens