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Manual Pages  — PW.CONF


pw.conf – format of the pw.conf configuration file



The file /etc/pw.conf contains configuration data for the pw(8) utility. The pw(8) utility is used for maintenance of the system password and group files, allowing users and groups to be added, deleted and changed. This file may be modified via the pw(8) command using the useradd command and the -D option, or by editing it directly with a text editor.

Each line in /etc/pw.conf is treated either a comment or as configuration data; blank lines and lines commencing with a ‘amp;#’ character are considered comments, and any remaining lines are examined for a leading keyword, followed by corresponding data.

Keywords recognized by pw(8) are:
  affect passwords generated for new users
reuseuids reuse gaps in uid sequences
reusegids reuse gaps in gid sequences
nispasswd path to the NIS passwd database
skeleton where to obtain default home contents
newmail mail to send to new users
logfile log user/group modifications to this file
home root directory for home directories
homemode permissions for home directory
shellpath paths in which to locate shell programs
shells list of valid shells (without path)
defaultshell default shell (without path)
defaultgroup default group
extragroups add new users to this groups
defaultclass place new users in this login class
  range of valid default user ids
  range of valid default group ids
expire_days days after which account expires
  days after which password expires

Valid values for defaultpasswd are:
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 second and third options are insecure and should be avoided if possible on a publicly accessible system. The first option requires that the superuser run passwd(1) to set a password before the account may be used. This may also be useful for creating administrative accounts. The final option causes pw(8) to respond by printing a randomly generated password on stdout. This is the preferred and most secure option. The pw(8) utility also provides a method of setting a specific password for the new user via a filehandle (command lines are not secure).

Both reuseuids and reusegids determine the method by which new user and group id numbers are generated. A ‘amp;yes’ in this field will cause pw(8) to search for the first unused user or group id within the allowed range, whereas a ‘amp;no’ will ensure that no other existing user or group id within the range is numerically lower than the new one generated, and therefore avoids reusing gaps in the user or group id sequence that are caused by previous user or group deletions. Note that if the default group is not specified using the defaultgroup keyword, pw(8) will create a new group for the user and attempt to keep the new user's uid and gid the same. If the new user's uid is currently in use as a group id, then the next available group id is chosen instead.

On NIS servers which maintain a separate passwd database to /etc/master.passwd, this option allows the additional file to be concurrently updated as user records are added, modified or removed. If blank or set to 'no', no additional database is updated. An absolute pathname must be used.

The skeleton keyword nominates a directory from which the contents of a user's new home directory is constructed. This is /usr/share/skel by default. The pw(8)'s -m option causes the user's home directory to be created and populated using the files contained in the skeleton directory.

To send an initial email to new users, the newmail keyword may be used to specify a path name to a file containing the message body of the message to be sent. To avoid sending mail when accounts are created, leave this entry blank or specify ‘amp;no’.

The logfile option allows logging of password file modifications into the nominated log file. To avoid creating or adding to such a logfile, then leave this field blank or specify ‘amp;no’.

The home keyword is mandatory. This specifies the location of the directory in which all new user home directories are created.

The homemode keyword is optional. It specifies the creation mask of the user's home directory and is modified by umask(2).

The shellpath keyword specifies a list of directories - separated by colons ‘amp;:’ - which contain the programs used by the login shells.

The shells keyword specifies a list of programs available for use as login shells. This list is a comma-separated list of shell names which should not contain a path. These shells must exist in one of the directories nominated by shellpath.

The defaultshell keyword nominates which shell program to use for new users when none is specified on the pw(8) command line.

The defaultgroup keyword defines the primary group (the group id number in the password file) used for new accounts. If left blank, or the word ‘amp;no’ is used, then each new user will have a corresponding group of their own created automatically. This is the recommended procedure for new users as it best secures each user's files against interference by other users of the system irrespective of the umask normally used by the user.

The extragroups keyword provides an automatic means of placing new users into groups within the /etc/groups file. This is useful where all users share some resources, and is preferable to placing users into the same primary group. The effect of this keyword can be overridden using the -G option on the pw(8) command line.

The defaultclass field determines the login class (See login.conf(5)) that new users will be allocated unless overwritten by pw(8).

The minuid, maxuid, mingid, maxgid keywords determine the allowed ranges of automatically allocated user and group id numbers. The default values for both user and group ids are 1000 and 32000 as minimum and maximum respectively. The user and group id's actually used when creating an account with pw(8) may be overridden using the -u and -g command line options.

The expire_days and password_days are used to automatically calculate the number of days from the date on which an account is created when the account will expire or the user will be forced to change the account's password. A value of ‘amp;0’ in either field will disable the corresponding (account or password) expiration date.


The maximum line length of /etc/pw.conf is 1024 characters. Longer lines will be skipped and treated as comments.




passwd(1), umask(2), group(5), login.conf(5), passwd(5), pw(8)

PW.CONF (5) March 30, 2007

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