Opening a .pub file
 

Someone tells me .pub is a file format for Microsoft Publisher, is it? Either way, can I open it in Linux?

OpenOffice.org might be able to, if you're lucky. Otherwise, google for a converter of some sort.

Convert it online to .pdf
https://createpdf.adobe.com/index.pl

You need to sign up and it's limited to 5 free conversions.

I believe MS Publisher files can be converted to compatible formats with Publisher itself, so that they can be opened with OpenOffice.org, Scribus etc.

Here's what other things files with .pub extension could be:

http://filext.com/detaillist.php?extdetail=pub

Regards
Simon

Ok, this thread is 10 years old (!) but I still found it through a web search looking for an answer to the same exact question.
Eventually I found my answer in the package manager nad it is called pub2odg, a command-line tool that converts a Ms Publisher (.pub) file to an OpenDocument (OpenOffice/LibreOffice) Draw document (.odg).