There is a command called
file that can recognize multiple file types both by the headers and by the contents of the files (when they are plain text).
I would like to know if there is a way to alter a file just to its header. To make an mp3 file look like a RAR archive, for example, but letting the rest of the file intact.
So, when you want, you can change the header of the file back to MP3 and it will work as before.
Is this even possible with software available in Ubuntu or in general?