Determining Types of Files With No Extension on Linux & OS X
Determining types of extensionless files on OS X and Linux
Being lazy and in a rush, I saved a download with its default name, thinking I’d remember what kind of file it was without adding an extension. Needless to say, I didn’t—but a quick search revealed a solution, and I’d suggest adding it to your toolkit. Hit up the link or run man file in your friendly local terminal emulator for more.