contains for each user the
name (login name, contains no upper case)
GCOS job number and box number
initial working directory
This is an ASCII file. Each field within each user's entry
is separated from the next by a colon.
The job and box numbers are separated by a comma.
Each user is separated from the next by a new-line.
If the password field is null, no password is demanded;
if the Shell field is null, the Shell itself
This file resides in directory /etc.
passwords, it can and does have general read
permission and can be used, for example,
to map numerical user ID's to names.
login(I), crypt(III), passwd(I)