YJL

I am trying to parse passwd and group files for login names, so this brought me to think about what characters are valid, which I never thought about before and always assumed it's /[a-z]+/.

Here is the explanation from the manpages of useradd and groupadd:

Usernames must start with a lower case letter or an underscore, followed by lower case letters, digits,
underscores, or dashes. They can end with a dollar sign. In regular expression terms: [a-z_][a-z0-9_-]*[$]?

Usernames may only be up to 32 characters long.

Groupnames must start with a lower case letter or an underscore, followed by lower case letters, digits,
underscores, or dashes. They can end with a dollar sign. In regular expression terms: [a-z_][a-z0-9_-]*[$]?

They even provide ready-to-go regular expressions for matching, but does anyone know about the ending dollar sign?

I am guessing it must be some sort of history, but I am not that old to know about it and I have never seen any login username contains dollar sign in any OS I have ever used.

I tried to find an answer on Internet, but didn't see any page talked about this (why would one?). However, there are some results about Windows login with ending dollar sign.

I have been using my username livibetter for more than five years. Few days ago, I noticed it got suggested!



Oh, yeah!

My real name doesn't get the same treat, even it has more results, though many are not about me, but I am listed at top 1. Actually 9 out of 10 at first page are my stuff.

When I started blogging here, I intended to disconnect myself from my username. So, if you try to search for my username and to get pages of this blog, you won't get many.

livibetter will still be my username because it's unique, my real name or initials of my real name isn't. That's the reason I don't use my real name often before, but I started to use it when I filled in a form if the field for name is labeled as name. If it's labeled as nickname, I will use my username. Once someone told me livibetter isn't a nickname at all, I don't disagree, so I let them call me by Yu, part of my first name.

If you see the footer of posts, you will read "Posted by P.". P. is my new nickname and signature, I just begin to use it to sign my stuff. It's not an abbreviation of a name but a word actually.

Anyway, have your username got suggested?