contains for each user the
name (login name, contains no upper case)
GCOS job number, box number, optional GCOS user-id
initial working directory
This is an ASCII file. Each field within each user's entry
is separated from the next by a colon.
The GCOS field is used only when communicating with that
system, and in other installations can contain
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.
getpwent(3), login(1), crypt(3), passwd(1), group(5)