The
utility is a command-line based editor for the system
user
and
group
files, allowing the superuser an easy to use and standardized way of adding,
modifying and removing users and groups.
Note that
only operates on the local user and group files.
NIS
users and groups must be
maintained on the
NIS
server.
The
utility handles updating the
passwd
master.passwd
group
and the secure and insecure
password database files, and must be run as root.
The first one or two keywords provided to
on the command line provide the context for the remainder of the arguments.
The keywords
user
and
group
may be combined with
adddelmodshow
or
next
in any order.
(For example,
showuserusershowshow user
and
user show
all mean the same thing.)
This flexibility is useful for interactive scripts calling
for user and group database manipulation.
Following these keywords, you may optionally specify the user or group name or numeric
id as an alternative to using the
-n name
-u uid
-g gid
options.
The following flags are common to most or all modes of operation:
-V etcdir
This flag sets an alternate location for the password, group and configuration files,
and may be used to maintain a user/group database in an alternate location.
If this switch is specified, the system
/etc/pw.conf
will not be sourced for default configuration data, but the file pw.conf in the
specified directory will be used instead (or none, if it does not exist).
The
-C
flag may be used to override this behaviour.
As an exception to the general rule where options must follow the operation
type, the
-V
flag may be used on the command line before the operation keyword.
-C config
By default,
reads the file
/etc/pw.conf
to obtain policy information on how new user accounts and groups are to be created.
The
-C
option specifies a different configuration file.
While most of the contents of the configuration file may be overridden via
command-line options, it may be more convenient to keep standard information in a
configuration file.
-q
Use of this option causes
to suppress error messages, which may be useful in interactive environments where it
is preferable to interpret status codes returned by
rather than messing up a carefully formatted display.
-N
This option is available in
add
and
modify
operations, and tells
to output the result of the operation without updating the user or group
databases.
You may use the
-P
option to switch between standard passwd and readable formats.
-Y
Using this option with any of the update modes causes
to run
make(1)
after changing to the directory
/var/yp
This is intended to allow automatic updating of
NIS
database files.
If separate passwd and group files are being used by
NIS
then use the
-y path
option to specify the location of the
NIS
passwd database so that
will concurrently update it with the system password
databases.
USER OPTIONS
The following options apply to the
useradd
and
usermod
commands:
-n name
Specify the user/account name.
-u uid
Specify the user/account numeric id.
Usually, you only need to provide one or the other of these options, as the account
name will imply the uid, or vice versa.
However, there are times when you need to provide both.
For example, when changing the uid of an existing user with
usermod
or overriding the default uid when creating a new account.
If you wish
to automatically allocate the uid to a new user with
useradd
then you should
not
use the
-u
option.
You may also provide either the account or userid immediately after the
useradduserdelusermod
or
usershow
keywords on the command line without using the
-n
or
-u
options.
-c comment
This field sets the contents of the passwd GECOS field, which normally contains up
to four comma-separated fields containing the user's full name, office or location,
and work and home phone numbers.
These sub-fields are used by convention only, however, and are optional.
If this field is to contain spaces, you need to quote the comment itself with double
quotes
`'
Avoid using commas in this field as these are used as sub-field separators, and the
colon
`:'
character also cannot be used as this is the field separator for the passwd
file itself.
-d dir
This option sets the account's home directory.
Normally, you will only use this if the home directory is to be different from the
default determined from
/etc/pw.conf
- normally
/home
with the account name as a subdirectory.
-e date
Set the account's expiration date.
Format of the date is either a UNIX time in decimal, or a date in
`dd-mmm-yy[yy]'
format, where dd is the day, mmm is the month, either in numeric or alphabetic format
('Jan', 'Feb', etc) and year is either a two or four digit year.
This option also accepts a relative date in the form
`+n[mhdwoy]'
where
`n'
is a decimal, octal (leading 0) or hexadecimal (leading 0x) digit followed by the
number of Minutes, Hours, Days, Weeks, Months or Years from the current date at
which the expiration date is to be set.
-p date
Set the account's password expiration date.
This field is similar to the account expiration date option, except that it
applies to forced password changes.
This is set in the same manner as the
-e
option.
-g group
Set the account's primary group to the given group.
group
may be defined by either its name or group number.
-G grouplist
Set additional group memberships for an account.
grouplist
is a comma, space or tab-separated list of group names or group numbers.
The user's name is added to the group lists in
/etc/group
and
removed from any groups not specified in
grouplist
Note: a user should not be added to their primary group with
grouplist
Also, group membership changes do not take effect for current user login
sessions, requiring the user to reconnect to be affected by the changes.
-L class
This option sets the login class for the user being created.
See
login.conf5
and
passwd(5)
for more information on user login classes.
-m
This option instructs
to attempt to create the user's home directory.
While primarily useful when adding a new account with
useradd
this may also be of use when moving an existing user's home directory elsewhere on
the file system.
The new home directory is populated with the contents of the
skeleton
directory, which typically contains a set of shell configuration files that the
user may personalize to taste.
Files in this directory are usually named
dot . Aq config
where the
dot
prefix will be stripped.
When
-m
is used on an account with
usermod
existing configuration files in the user's home directory are
not
overwritten from the skeleton files.
When a user's home directory is created, it will by default be a subdirectory of the
basehome
directory as specified by the
-b
option (see below), bearing the name of the new account.
This can be overridden by the
-d
option on the command line, if desired.
-M mode
Create the user's home directory with the specified
mode
modified by the current
umask(2).
If omitted, it is derived from the parent process'
umask(2).
This option is only useful in combination with the
-m
flag.
-k dir
Set the
skeleton
directory, from which basic startup and configuration files are copied when
the user's home directory is created.
This option only has meaning when used with the
-d
or
-m
flags.
-s shell
Set or changes the user's login shell to
shell
If the path to the shell program is omitted,
searches the
shellpath
specified in
/etc/pw.conf
and fills it in as appropriate.
Note that unless you have a specific reason to do so, you should avoid
specifying the path - this will allow
to validate that the program exists and is executable.
Specifying a full path (or supplying a blank "" shell) avoids this check
and allows for such entries as
/nonexistent
that should be set for accounts not intended for interactive login.
-h fd
This option provides a special interface by which interactive scripts can
set an account password using
.
Because the command line and environment are fundamentally insecure mechanisms
by which programs can accept information,
will only allow setting of account and group passwords via a file descriptor
(usually a pipe between an interactive script and the program).
shbashksh
and
perl
all possess mechanisms by which this can be done.
Alternatively,
will prompt for the user's password if
-h 0
is given, nominating
stdin
as the file descriptor on which to read the password.
Note that this password will be read only once and is intended
for use by a script rather than for interactive use.
If you wish to have new password confirmation along the lines of
passwd(1),
this must be implemented as part of an interactive script that calls
.
If a value of
`-'
is given as the argument
fd
then the password will be set to
`*'
,
rendering the account inaccessible via password-based login.
-H fd
Read an encrypted password string from the specified file descriptor.
This is like
-h
but the password should be supplied already encrypted in a form
suitable for writing directly to the password database.
It is possible to use
useradd
to create a new account that duplicates an existing user id.
While this is normally considered an error and will be rejected, the
-o
option overrides the check for duplicates and allows the duplication of
the user id.
This may be useful if you allow the same user to login under
different contexts (different group allocations, different home
directory, different shell) while providing basically the same
permissions for access to the user's files in each account.
The
useradd
command also has the ability to set new user and group defaults by using the
-D
option.
Instead of adding a new user,
writes a new set of defaults to its configuration file,
/etc/pw.conf
When using the
-D
option, you must not use either
-n name
or
-u uid
or an error will result.
Use of
-D
changes the meaning of several command line switches in the
useradd
command.
These are:
-D
Set default values in
/etc/pw.conf
configuration file, or a different named configuration file if the
-C config
option is used.
-b dir
Set the root directory in which user home directories are created.
The default value for this is
/home
but it may be set elsewhere as desired.
-e days
Set the default account expiration period in days.
Unlike use without
-D
the argument must be numeric, which specifies the number of days after creation when
the account is to expire.
A value of 0 suppresses automatic calculation of the expiry date.
-p days
Set the default password expiration period in days.
-g group
Set the default group for new users.
If a blank group is specified using
-g
then new users will be allocated their own private primary group
with the same name as their login name.
If a group is supplied, either its name or uid may be given as an argument.
-G grouplist
Set the default groups in which new users are granted membership.
This is a separate set of groups from the primary group, and you should avoid
nominating the same group as both primary and extra groups.
In other words, these extra groups determine membership in groups
other than
the primary group.
grouplist
is a comma-separated list of group names or ids, and are always
stored in
/etc/pw.conf
by their symbolic names.
-L class
This option sets the default login class for new users.
-k dir
Set the default
skeleton
directory, from which prototype shell and other initialization files are copied when
creates a user's home directory.
See description of
-k
for naming conventions of these files.
-u min , max
-i min , max
These options set the minimum and maximum user and group ids allocated for new accounts
and groups created by
.
The default values for each is 1000 minimum and 32000 maximum.
min
and
max
are both numbers, where max must be greater than min, and both must be between 0
and 32767.
In general, user and group ids less than 100 are reserved for use by the system,
and numbers greater than 32000 may also be reserved for special purposes (used by
some system daemons).
-w method
The
-w
option sets the default method used to set passwords for newly created user accounts.
method
is one of:
no
disable login on newly created accounts
yes
force the password to be the account name
none
force a blank password
random
generate a random password
The
`random'
or
`no'
methods are the most secure; in the former case,
generates a password and prints it to stdout, which is suitable where you issue
users with passwords to access their accounts rather than having the user nominate
their own (possibly poorly chosen) password.
The
`no'
method requires that the superuser use
passwd(1)
to render the account accessible with a password.
-y path
This sets the pathname of the database used by
NIS
if you are not sharing
the information from
/etc/master.passwd
directly with
NIS
You should only set this option for
NIS
servers.
The
userdel
command has only three valid options.
The
-n name
and
-u uid
options have already been covered above.
The additional option is:
-r
This tells
to remove the user's home directory and all of its contents.
The
utility errs on the side of caution when removing files from the system.
Firstly, it will not do so if the uid of the account being removed is also used by
another account on the system, and the 'home' directory in the password file is
a valid path that commences with the character
`/'
Secondly, it will only remove files and directories that are actually owned by
the user, or symbolic links owned by anyone under the user's home directory.
Finally, after deleting all contents owned by the user only empty directories
will be removed.
If any additional cleanup work is required, this is left to the administrator.
Mail spool files and crontabs are always removed when an account is deleted as these
are unconditionally attached to the user name.
Jobs queued for processing by
at
are also removed if the user's uid is unique and not also used by another account on the
system.
The
usershow
command allows viewing of an account in one of two formats.
By default, the format is identical to the format used in
/etc/master.passwd
with the password field replaced with a
`*'
If the
-P
option is used, then
outputs the account details in a more human readable form.
If the
-7
option is used, the account details are shown in v7 format.
The
-a
option lists all users currently on file.
Using
-F
forces
to print the details of an account even if it does not exist.
The command
usernext
returns the next available user and group ids separated by a colon.
This is normally of interest only to interactive scripts or front-ends
that use
.
GROUP OPTIONS
The
-C
and
-q
options (explained at the start of the previous section) are available
with the group manipulation commands.
Other common options to all group-related commands are:
-n name
Specify the group name.
-g gid
Specify the group numeric id.
As with the account name and id fields, you will usually only need
to supply one of these, as the group name implies the uid and vice
versa.
You will only need to use both when setting a specific group id
against a new group or when changing the uid of an existing group.
-M memberlist
This option provides an alternative way to add existing users to a
new group (in groupadd) or replace an existing membership list (in
groupmod).
memberlist
is a comma separated list of valid and existing user names or uids.
-m newmembers
Similar to
-M
this option allows the
addition
of existing users to a group without replacing the existing list of
members.
Login names or user ids may be used, and duplicate users are
silently eliminated.
-d oldmembers
Similar to
-M
this option allows the
deletion
of existing users from a group without replacing the existing list of
members.
Login names or user ids may be used, and duplicate users are
silently eliminated.
groupadd
also has a
-o
option that allows allocation of an existing group id to a new group.
The default action is to reject an attempt to add a group, and this option overrides
the check for duplicate group ids.
There is rarely any need to duplicate a group id.
The
groupmod
command adds one additional option:
-l name
This option allows changing of an existing group name to
`name'
The new name must not already exist, and any attempt to duplicate an existing group
name will be rejected.
Options for
groupshow
are the same as for
usershow
with the
-g gid
replacing
-u uid
to specify the group id.
The
-7
option does not apply to the
groupshow
command.
The command
groupnext
returns the next available group id on standard output.
USER LOCKING
The
utility
supports a simple password locking mechanism for users; it works by
prepending the string
`*LOCKED*'
to the beginning of the password field in
master.passwd
to prevent successful authentication.
The
lock
and
unlock
commands take a user name or uid of the account to lock or unlock,
respectively.
The
-V
-C
and
-q
options as described above are accepted by these commands.
NOTES
For a summary of options available with each command, you can use
pw [command] help
For example,
pw useradd help
lists all available options for the useradd operation.
The
utility allows 8-bit characters in the passwd GECOS field (user's full name,
office, work and home phone number subfields), but disallows them in
user login and group names.
Use 8-bit characters with caution, as connection to the Internet will
require that your mail transport program supports 8BITMIME, and will
convert headers containing 8-bit characters to 7-bit quoted-printable
format.
sendmail(8)
does support this.
Use of 8-bit characters in the GECOS field should be used in
conjunction with the user's default locale and character set
and should not be implemented without their use.
Using 8-bit characters may also affect other
programs that transmit the contents of the GECOS field over the
Internet, such as
fingerd(8),
and a small number of TCP/IP clients, such as IRC, where full names
specified in the passwd file may be used by default.
The
utility writes a log to the
/var/log/userlog
file when actions such as user or group additions or deletions occur.
The location of this logfile can be changed in
pw.conf5.
FILES
/etc/master.passwd
The user database
/etc/passwd
A Version 7 format password file
/etc/login.conf
The user capabilities database
/etc/group
The group database
/etc/master.passwd.new
Temporary copy of the master password file
/etc/passwd.new
Temporary copy of the Version 7 password file
/etc/group.new
Temporary copy of the group file
/etc/pw.conf
Pw default options file
/var/log/userlog
User/group modification logfile
EXIT STATUS
The
utility returns EXIT_SUCCESS on successful operation, otherwise
returns one of the
following exit codes defined by
sysexits(3)
as follows:
EX_USAGE
Command line syntax errors (invalid keyword, unknown option).
EX_NOPERM
Attempting to run one of the update modes as non-root.
EX_OSERR
Memory allocation error.
Read error from password file descriptor.
EX_DATAERR
Bad or invalid data provided or missing on the command line or
via the password file descriptor.
Attempted to remove, rename root account or change its uid.
EX_OSFILE
Skeleton directory is invalid or does not exist.
Base home directory is invalid or does not exist.
Invalid or non-existent shell specified.
EX_NOUSER
User, user id, group or group id specified does not exist.
User or group recorded, added, or modified unexpectedly disappeared.
EX_SOFTWARE
No more group or user ids available within specified range.
The
utility was written to mimic many of the options used in the SYSV
shadow
support suite, but is modified for passwd and group fields specific to
the
BSD 4.4
operating system, and combines all of the major elements
into a single command.
