Someone who uses arch linux.
You can typically recognize them by their profound lack of social skills and overpowering need to tell anyone and everyone about how they use arch and how great it is. They typically think of themselves as
intellectually superior and consider anyone who doesn't use arch a low IQ mongoloid, despite the fact that installing and using arch is no more difficult than assembling ikea furniture.
However, it is unlikely that you'll ever need to distinguish an arch user since as stated above they'll have told you long before you even thought about them being one.
Lastly, telling them that arch isn't mankinds greatest achievement will cause them to contort and
eventually spontaneously combust.