1PASSWD(5) File Formats Manual PASSWD(5)
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6 passwd - password files
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9 Passwd files are files consisting of newline separated records, one per
10 user, containing ten colon (``:'') separated fields. These fields are
11 as follows:
12 name user's login name
14 password user's encrypted password
15 uid user's id
16 gid user's login group id
17 class user's general classification (unused)
18 change password change time
19 expire account expiration time
20 gecos general information about the user
21 home_dir user's home directory
22 shell user's login shell
23 The name field is the login used to access the computer account, and
25 the uid field is the number associated with it. They should both be
26 unique across the system (and often across a group of systems) since
27 they control file access.
28 While it is possible to have multiple entries with identical login
30 names and/or identical user id's, it is usually a mistake to do so.
31 Routines that manipulate these files will often return only one of the
32 multiple entries, and that one by random selection.
33 The login name must never begin with a hyphen (``-''); also, it is
35 strongly suggested that neither upper-case characters or dots (``.'')
36 be part of the name, as this tends to confuse mailers. No field may
37 contain a colon (``:'') as this has been used historically to separate
38 the fields in the user database.
39 The password field is the encrypted form of the password. If the pass‐
41 word field is empty, no password will be required to gain access to the
42 machine. This is almost invariably a mistake. Because these files
43 contain the encrypted user passwords, they should not be readable by
44 anyone without appropriate privileges.
45 The group field is the group that the user will be placed in upon
47 login. Since this system supports multiple groups (see groups(1)) this
48 field currently has little special meaning.
49 The class field is currently unused. In the near future it will be a
51 key to a termcap(5) style database of user attributes.
52 The change field is the number in seconds, GMT, from the epoch, until
54 the password for the account must be changed. This field may be left
55 empty to turn off the password aging feature.
56 The expire field is the number in seconds, GMT, from the epoch, until
58 the account expires. This field may be left empty to turn off the
59 account aging feature.
60 The gecos field normally contains comma (``,'') separated subfields as
62 follows:
63 name user's full name
65 office user's office number
66 wphone user's work phone number
67 hphone user's home phone number
68 This information is used by the finger(1) program.
70 The user's home directory is the full UNIX path name where the user
72 will be placed on login.
73 The shell field is the command interpreter the user prefers. If the
75 shell field is empty, the Bourne shell (/bin/sh) is assumed.
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78 chpass(1), login(1), passwd(1), getpwent(3), mkpasswd(8), vipw(8)
79 adduser(8)
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82 User information should (and eventually will) be stored elsewhere.
837th Edition May 8, 1989 PASSWD(5)