There is one entry per line, and each line has the format:
account:password:UID:GID:GECOS:directory:shell
The field descriptions are:
account the name of the user on the system. It
should not contain capital letters.
password the encrypted user password or a star.
UID the numerical user ID.
GID the numerical primary group ID for this
user.
GECOS This field is optional and only used for
informational purposes. Usually, it con-
tains the full user name. GECOS means
General Electric Comprehensive Operating
System, which has been renamed to GCOS
when GE's large systems division was sold
to Honeywell. Dennis Ritchie has
reported: "Sometimes we sent printer out-
put or batch jobs to the GCOS machine.
The gcos field in the password file was a
place to stash the information for the
$IDENTcard. Not elegant."
directory the user's $HOME directory.
shell the program to run at login (if empty,
use /bin/sh). If set to a non-existing
executable, the user will be unable to
login through login(1).