If you use KDE you'll know that KPrinter handles printing tasks for applications in KDE. What you may not know is KPrinter can be used as a standalone package.
If you want to print a file, you don't need to open an application. Run KPrinter and print what you like.
You can either launch it from the command line and select the file to print:
or pass it an argument:
$ cat file | kprinter --stdin
That's about it.