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Re: usernames that start with capital letter?

Ron Johnson wrote:
> Subject: Re: usernames that start with capital letter?
> Why aren't they recommended?

A lot of things are technically allowed but historically were terrible
problems in practice.  Mixed case user names.  Spaces in user names.
Unusual characters in user names.  All of have been terrible sources
of problems interoperating with other systems.  Mostly it has been a
long evolutionary climb from lower case us-ascii toward general 8-bit
clean interfaces.  For example email allows for it with RFC2821 but
recommends against it.

  The local-part of a mailbox MUST BE treated as case sensitive.
  Therefore, SMTP implementations MUST take care to preserve the case
  of mailbox local-parts.  Mailbox domains are not case sensitive.  In
  particular, for some hosts the user "smith" is different from the
  user "Smith".  However, exploiting the case sensitivity of mailbox
  local-parts impedes interoperability and is discouraged.

And this doesn't take into consideration other related systems such as
NIS/YP and mixed system tools such as ftp and so forth.  Remember Unix
is all about lower case (and often no vowels) and so assumptions have
been made all around.

If you really want to stress things then add spaces and utf-8
characters too.  These days it /should/ work.  But I wouldn't
recommend it.  :-)

Also note that there must be at least one lower case letter or getty
will assume that you are using an upper case only terminal and will
set up the tty driver to map upper case to lower case with iuclc.  The
old getty manual used to recommend using only lower case letters.

But I don't know of any specific problems with mixed case today.  The
best advice I would have is to try it and see.  File bugs if there are
problems.  But note that it is a path less well traveled.


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