
Question: what is "Charlie &" for the root user? I didn't gave "Charlie &" for gecos field, I think I didn't gave any at all.
ps.: the "/sbin/nologin" doesn't matters, I just tested something

Question: what is "Charlie &" for the root user? I didn't gave "Charlie &" for gecos field, I think I didn't gave any at all.
ps.: the "/sbin/nologin" doesn't matters, I just tested something
That is the default you get if you leave it out. It comes from Charlie (the) Root (user) and I've seen it show up as a name over the years in articles and papers. Don't know where it orignated but at least before 1995.
The & in the Gecos field is automatically replaced by root.
It is mentioned e.g in Matt Bishops paper (page 6). And it has its own wikipedia article which says that it is a reference to the baseball player Charlie Root