# Ubuntu – What are “unknown” file types?

files

In /home// are, among others, the following entries. Can anyone tell me what these ”unknown” file types are? Are they legitimate?

.ICEauthority          2.4kB        unknown
.profile               675 bytes    plain text document
.Xauthority            48 bytes     unknown
.xsession-errors       28.5 kB      plain text document
.xsession-errors.old   7.9 kB       backup file


The file .Xauthority contains a single line of meaningless (to me) letters and symbols.

The file .pulse-cookie contains characters like the following in gedit, most of them highlighted in red:

\EC\BD\C8\D5\ED\C2\EC\AF#\B6v\EE\83\F7\C2\C8vnr\EA


.ICEauthority contains mostly readable phrases, almost all like these, and mostly highlighted in red:

unix/Pax:/tmp/.ICE-unix/1494\00#MIT-MAGIC-COOKIE-\00


What is the difference between the paths shown in these 2 lines? And specifically, what does the @ symbol mean in this example?

I have read that these files have a security function, and that is why I am concerned. I am new to Ubuntu and don't know whether “unknown” file type is as ominous in Ubuntu as it is in Windows. My computer is not networked to any other, and was not attached to the Internet when these files were created.

Are these “unknown” files any indication of intrusion or hijack of my system? Anything I should worry about?

• .ICEauthority is explained here.
• .XAuthority is explained here.
• .xsession-errors is an error log.
• .pulse-cookie is a PulseAudio authentication cookie.
• .profile contains commands which are executed when you log in.