David L. Nugent.
Password Maintenance
$Id: pw.8,v 1.3 1996/11/18 03:09:01 davidn Exp $
.Dd November 13, 1996 .Dt PW 8 .Os .Sh NAME .Nm pw .Nd create, remove and modify system users and groups .Sh SYNOPSIS .Nm pw .Ar useradd .Op name|uid .Op Fl C Ar config .Op Fl q .Op Fl n Ar name .Op Fl u Ar uid .Op Fl c Ar comment .Op Fl d Ar dir .Op Fl e Ar date .Op Fl p Ar date .Op Fl g Ar group .Op Fl G Ar grouplist .Op Fl m .Op Fl k Ar dir .Op Fl s Ar shell .Op Fl o .Op Fl L Ar class .Op Fl h Ar fd .Nm pw .Ar useradd .Op name|uid .Op Fl D .Op Fl C Ar config .Op Fl q .Op Fl b Ar dir .Op Fl e Ar days .Op Fl p Ar days .Op Fl g Ar group .Op Fl G Ar grouplist .Op Fl k Ar dir .Op Fl u Ar min,max .Op Fl i Ar min,max .Op Fl w Ar method .Op Fl s Ar shell .Nm pw .Ar userdel .Op name|uid .Op Fl n Ar name .Op Fl u Ar uid .Op Fl r .Nm pw .Ar usermod .Op name|uid .Op Fl C Ar config .Op Fl q .Op Fl n Ar name .Op Fl u Ar uid .Op Fl c Ar comment .Op Fl d Ar dir .Op Fl e Ar date .Op Fl p Ar date .Op Fl g Ar group .Op Fl G Ar grouplist .Op Fl l Ar name .Op Fl m .Op Fl k Ar dir .Op Fl s Ar shell .Op Fl L Ar class .Op Fl h Ar fd .Nm pw .Ar usershow .Op name|uid .Op Fl n Ar name .Op Fl u Ar uid .Op Fl F .Op Fl p .Op Fl a .Nm pw .Ar groupadd .Op group|gid .Op Fl C Ar config .Op Fl q .Op Fl n Ar group .Op Fl g Ar gid .Op Fl o .Op Fl h Ar fd .Nm pw .Ar groupdel .Op Fl n Ar name .Op Fl g Ar gid .Nm pw .Ar groupmod .Op Fl C Ar config .Op Fl q .Op Fl F .Op Fl n Ar name .Op Fl g Ar gid .Op Fl l Ar name .Op Fl h Ar fd .Nm pw .Ar groupshow .Op Fl n Ar name .Op Fl g Ar gid .Op Fl F .Op Fl p .Op Fl a .Sh DESCRIPTION .Nm pw is a command-line based editor for the system .Em user and .Em group files, allowing the superuser and easy to use and standardised way of adding, modifying and removing users and groups. Note that .Nm pw only operates on the local user and group files; NIS users and groups must be maintained on the NIS server. .Nm pw handles updating the passwd, master.passwd, group and the secure and insecure password database files, and must be run as root.
p The first one or two keywords provided on .Xr pw 8 's command line provide the context for the remainder of the arguments. One of the keywords .Ar user and .Ar group may be combined or provided separately with .Ar add , .Ar del , .Ar mod or .Ar show , and may be specified in either order (ie. showuser, usershow, show user and user show are all considered to be the same thing). This flexiblity is useful for interactive scripts which call .Nm pw for the actual 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 .Fl n Ar name , .Fl u Ar uid , .Fl g Ar gid switches.
p The following flags are common to most modes of operation:
p l -tag -width "-C config" t Fl C Ar config By default, .Nm pw reads the file
a /etc/pw.conf to obtain policy information on how new user accounts and groups are to be created, and the .Fl c option overrides this to read a different file. Most of the contents in the configuration file may be overridden via command line options, but it may be more useful to set up standard information for addition of new accounts in the configuration file. t Fl q Use of this option causes .Nm pw to suppress error messages, which may be useful in interactive environments where it is preferable to interpret status codes returned by .Nm pw rather than messing up a carefully formatted display. .El
p .Sh USER OPTIONS The following options apply to the .Ar useradd , and .Ar usermod , commands:
p l -tag -width "-C config" t Fl n Ar name Specifies the user/account name. t Fl u Ar uid Specifies the user/account numeric id.
p Usually, you need only to provide one or the other of these options, as the account name will imply the uid, and vice verca. Also, you may provide either the account or userid immediately after the .Ar useradd , .Ar userdel , .Ar usermod or .Ar usershow keyword on the command line without the need to use .Ql Fl n or .Ql Fl u . There are times, however, were you need to provide both. For example, when changing the uid of an existing user with .Ar usermod , or overriding the default uid when creating a new account. If you wish .Nm pw to automatically allocate the uid to a new user on .Ar useradd , then you should .Em not use the .Ql Fl u switch. .El
p Options available with both .Ar useradd and .Ar usermod are: l -tag -width "-G grouplist" t Fl c Ar 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, 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 .Ql " . Avoid using commas in this field as these are used as sub-field separators, and the colon .Ql : character also cannot be used as this is the field separator in the passwd file. t Fl d Ar 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 (which is determined from pw.conf, which specifies the base home directory - normally /home - with the account name as a subdirectory). t Fl e Ar date Sets the account's expiration date. Format of the date is either a UNIX time in decimal, or a date in .Ql 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 .Ql +n[mhdwoy] where .Ql 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 expiry date is to be set. t Fl p Ar date Sets the account's password expiration date. This field is identical to the account expiration date option, except that it applies to forced password changes. The same formats are accepted as with the account expiratino option. t Fl g Ar group Sets the account's primary group to the given group. .Ar group may be either the group name or its corresponding group id number. t Fl G Ar grouplist Sets the additional groups to which an account belongs. .Ar grouplist is a comma-separated list or group names or group ids. When adding a user, the user's name is added to the group lists in
a /etc/group , and when editing a user, the user's name is also added to the group lists, and removed from any groups not specified in .Ar grouplist . Note: a user should not be added to their primary group in
a /etc/group . Also, group membership changes do not take effect immediately for current logins, only logins subsequent to the change. t Fl m This option instructs .Nm pw to attempt to create the user's home directory. While primarily useful when adding a new account with .Ar useradd , this may also be of use when moving an existing user's home directory elsewhere on the filesystem. The new home directory is populated with the contents of the .Ar skeleton directory, which typically contains a set of shell configuration files that the user may personalise to taste. When .Ql Fl m is used on an account with .Ar usermod , any existing configuration files in the user's home directory are .Em not overwritten with the prototype files.
p When a user's home directory is created, it will be default be as a subdirectory of the .Ar basehome directory specified with the .Ql Fl b Ar dir option (see below), and will be named the same as the account. This may be overridden with the .Ql Fl d Ar dir option on the command line, if desired. t Fl k Ar dir Sets the .Ar skeleton subdirectory, from which the basic startup and configuration files are copied when the user's home directory is created. This option only has meaning when used with .Ql Fl D (see below) or .Ql Fl m . t Fl s Ar shell Sets or changes the user's login shell to .Ar shell . If the path to the shell program is omitted, .Nm pw searches the .Ar shellpath specified in
a /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 .Nm pw 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 .Ql /nonexistent that should be set for accounts not intended for interactive login. t Fl L Ar class Sets the .Em class field in the user's passwd record. This field is not currently used, but will be in the future used to specify a .Em termcap entry like tag (see .Xr passwd 5 for details). t Fl h Ar fd This option provides a special interface by which interactive scripts can set an account password using .Nm pw . Because the command line and environment are fundamental insecure mechanisms by which programs can accept information, .Nm pw will only allow setting of account and group passwords via a file descriptor (usually a pipe between an interactive script and the program). .Ar sh , .Ar bash , .Ar ksh and .Ar perl all posses mechanisms by which this can be done. Alternatively, .Nm pw will prompt for the user's password if .Ql Fl h Ar 0 is given, nominating .Em stdin as the file descriptor on which to read the password. Note that this password will be read once and once only and is intended for use by a script or similar rather than interactive use. If you wish to have new password confirmation along the lines of .Xr passwd 1 , this must be implemented as part of the interactive script that calls .Nm pw .
p If a value of .Ql - is given as the argument .Ar fd , then the password will be set to .Ql * , rendering the account inaccessible via passworded login. .El
p It is possible to use .Ar useradd to create a new account that duplicates an existing user id. While this is normally considered an error and will be rejected, the .Ql Fl o switch 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.
p The .Ar useradd command also has the ability to set new user and group defaults by using the .Ql Fl D switch. Instead of adding a new user, .Nm pw writes a new set of defaults to its configuration file,
a /etc/pw.conf . When using the .Ql Fl D switch, you must not use either .Ql Fl n Ar name or .Ql Fl u Ar uid or an error will result. Use of .Ql Fl D adds switches and changes the meaning of several command line switches in the .Ar useradd command. These are: l -tag -width "-G grouplist" t Fl D Set default values in
a /etc/pw.conf configuration file, or a different named configuration file if the .Ql Fl C Ar config switch is used. t Fl b Ar dir Sets the root directory in which user home directories are created. The default value for this is .Ql /home , but it may be set elsewhere as desired. t Fl e Ar days Sets the default account expiration period in days. Unlike use without .Ql Fl 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. t Fl p Ar days Sets the default password expiration period in days. t Fl g Ar group Sets the default group for new users. If a blank group is specified using .Ql Fl g Ar "" , then new users will be allocated their own private primary group (a new group created with the same name as their login name). If a group is supplied, either its name or uid may be given as an argument. t Fl G Ar grouplist Sets the default groups in which new users are made members. This is a separate set of groups from the primary group, and you should avoid nominating the same group as both the primary and in extra groups. In other words, these extra groups determine membership in groups .Em other than the primary group. .Ar grouplist is a comma-separated list of group names or ids, or a mixture of both, and are always stored in
a /etc/pw.conf by their symbolic names. t Fl k Ar dir Sets the default .Em skeleton directory, from which prototype shell and other initialisation files are copied when .Nm pw creates a user's home directory. t Fl u Ar min,max t Fl i Ar min,max These switches set the minimum and maximum user and group ids allocated for new accounts and groups created by .Nm pw . The default values for each is 1000 minimum and 32000 maximum. .Ar min and .Ar 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). t Fl w Ar method The .Ql Fl w switch sets the default method used to set passwords for newly created user accounts. .Ar method is one of:
p l -tag -width random -offset indent -compact t no disables login on newly created accounts t yes forces the password to be the account name t none forces a blank password t random Generates a random password .El
p The .Ql random or .Ql no methods are the most secure; in the former case, .Nm pw 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 .Ql no method requires that the superuser use .Xr passwd 1 to render the account accessible with a password. .El
p The .Ar userdel command has only three valid switches. The .Ql Fl n Ar name and .Ql Fl u Ar uid switches have already been covered above. The additional switch is: l -tag -width flag t Fl r This tells .Nm pw to remove the user's home directory and all of its contents. .Nm pw 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 .Ql / . 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 adminstrator. .El
p 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 .Ar at are also removed if the user's uid is unique (not also used by another account on the system).
p The .Ar usershow command allows viewing of an account in one of two formats. By default, the format is identical to the format used in
a /etc/master.passwd with the password field replaced with a .Ql * . Class, account and password expiration fields will be blank or zero zero unless the user running .Nm pw has root priviledges, as the secure password file where these reside is not accessible to non-root users. If the .Ql Fl p switch is used, then .Nm pw outputs the account details in a more human readable form. The .Ql Fl a switch lists all users currently on file.
p .Sh GROUP OPTIONS The .Ql Fl C Ar config and .Ql Fl q options (explained at the start of the previous section) are available with the .Ar groupadd and .Ar groupmod commands. Other common options to all group-related commands are: l -tag -width "-n name" t Fl n Ar name Specifies the group name. t Fl g Ar gid Specifies the group numeric id.
p As with the account name and id fields, yo uwill 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. .El
p .Ar groupadd also has a .Ql Fl o option that allows allocation of an existing group id to 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.
p The .Ar groupmod command adds one additonal switch:
p l -tag -width "-l name" t Fl l Ar name This option allows changing of an existing group name to .Ql name . The new name must not already exist, and any attempt to duplicate an existing group name will be rejected. .El
p Options for .Ar groupshow are the same as for .Ar usershow , with the .Ql Fl g Ar gid replacing .Ql Fl u Ar uid to specify the group id.
p .Sh NOTES For a summary of options available with each command, you can use .Dl pw [command] help For example, .Dl pw useradd help lists all available options for the useradd operation. .Sh FILES l -tag -width /etc/master.passwd.new -compact t Pa /etc/master.passwd The user database t Pa /etc/passwd A Version 7 format password file t Pa /etc/group The group database t Pa /etc/master.passwd.new Temporary copy of the master password file t Pa /etc/passwd.new Temporary copy of the Version 7 password file t Pa /etc/group.new Temporary copy of the group file t Pa /etc/pw.conf Pw default options file .El .Sh SEE ALSO .Xr pw.conf 5 , .Xr passwd 1 , .Xr chpass 1 , .Xr passwd 5 , .Xr group 5 , .Xr pwd_mkdb 8 , .Xr vipw 5 .Sh HISTORY .Nm pw was written to mimick many of the options used in the Linux .Em shadow suite, but is modified for passwd and group fields specific to the BSD 4.4 operating system.