how do you handle multiple accounts?

[HEDRICK at RUTGERS.ARPA]

From:  Charles Hedrick <HEDRICK at RUTGERS.ARPA>

We have a Pyramid Unix system which will be populated mostly by
students doing coursework.  A given student may be taking more
than one course.  We would like to be able to know how much time
each course is using (so we can sit on faculty who give 
unreasonable assignments).  On the DEC-20, there are three
separate object:
  users
  directories
  accounts
Each student has his own userid and directory.  Each course has an
account.  When a student logs in, he specifies both.   We are not so
naive as to believe we can get entirely accurate data from students on
which project they are working on, but the results seem fairly 
reasonable.  As far as I can see, Unix does not have anything like
an account.  We are considering two approaches.  I wonder whether
anyone has a better idea, or sees any problems with these approaches:

1) add account strings to Unix:  Will involve modifying LOGIN
to ask for an account, somebody (the shell?) to remember which
was specified, and whoever writes the WTMP file at logout to
add an account field to WTMP.  Then of course every program that
plays with WTMP, and all the accounting software, must be changed
to know about the account.

2) encode it in the user name.  If Smith is registered for
courses 431 and 510, the password file will contain

smith:*:123:1000:John Smith:/usr/smith
431.sss::123:431:John Smith:/usr/smith
510.sss::123:510:John Smith:/usr/smith

Where sss are his initials.  The idea is that he will log in
by using his course and initials, but the directory and mail
will all use the real name.  As all incarnations of a user
have the same uid, he will have access to all files at all times.
We will have to modify MAIL to that all incarnations of a user
read the main mail file.  That's the only change I see so far,
except to the program that prints our final usage reports.
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