CHM is a proprietary file format from Microsoft used for help files. You can view these files with Kchmviewer, which is quite a good application for KDE, offering a lot of options. To install it, just do the usual apt-get install kchmviewer as root.
You can configure font sizes, how it behaves, what engine to use for displaying the HTML files. You can add bookmarks or even see the HTML source for the currently viewing page. It also has an option to extract HTML files into a directory of your choice, breaking the whole CHM file into HTML files readable with a usual web browser.
The last stable version of KchmViewer is 3.1, and the development release at the time of writing is 4.0beta3.
Converting CHM to PDF using the chm2pdf tool
For converting the file to PDF, there is an open-source tool called chm2pdf included in the repositories as well. To install it type apt-get install chm2pdf as root, and to use it, all you have to do is:
chm2pdf --webpage chm_file.chm
A PDF file with the name chm_file.pdf will be generated, readable with any PDF reader like KPDF. The tool provides many other options for the newly generated PDF file, for a complete list see man chm2pdf.
Updated: Jul 03, 2008 (Created: Jul 03, 2008)