'\" t .\" Title: groupmems .\" Author: George Kraft, IV .\" Generator: DocBook XSL Stylesheets vsnapshot .\" Date: 07/02/2024 .\" Manual: System Management Commands .\" Source: shadow-utils 4.16.0 .\" Language: English .\" .TH "GROUPMEMS" "8" "07/02/2024" "shadow\-utils 4\&.16\&.0" "System Management Commands" .\" ----------------------------------------------------------------- .\" * Define some portability stuff .\" ----------------------------------------------------------------- .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .\" http://bugs.debian.org/507673 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" ----------------------------------------------------------------- .\" * set default formatting .\" ----------------------------------------------------------------- .\" disable hyphenation .nh .\" disable justification (adjust text to left margin only) .ad l .\" ----------------------------------------------------------------- .\" * MAIN CONTENT STARTS HERE * .\" ----------------------------------------------------------------- .SH "NAME" groupmems \- administer members of a user\*(Aqs primary group .SH "SYNOPSIS" .HP \w'\fBgroupmems\fR\ 'u \fBgroupmems\fR \-a\ \fIuser_name\fR | \-d\ \fIuser_name\fR | [\-g\ \fIgroup_name\fR] | \-l | \-p .SH "DESCRIPTION" .PP The \fBgroupmems\fR command allows a user to administer their own group membership list without the requirement of superuser privileges\&. The \fBgroupmems\fR utility is for systems that configure its users to be in their own name sake primary group (i\&.e\&., guest / guest)\&. .PP Only the superuser, as administrator, can use \fBgroupmems\fR to alter the memberships of other groups\&. .SH "OPTIONS" .PP The options which apply to the \fBgroupmems\fR command are: .PP \fB\-a\fR, \fB\-\-add\fR\ \&\fIuser_name\fR .RS 4 Add a user to the group membership list\&. .sp If the /etc/gshadow file exist, and the group has no entry in the /etc/gshadow file, a new entry will be created\&. .RE .PP \fB\-d\fR, \fB\-\-delete\fR\ \&\fIuser_name\fR .RS 4 Delete a user from the group membership list\&. .sp If the /etc/gshadow file exist, the user will be removed from the list of members and administrators of the group\&. .sp If the /etc/gshadow file exist, and the group has no entry in the /etc/gshadow file, a new entry will be created\&. .RE .PP \fB\-g\fR, \fB\-\-group\fR\ \&\fIgroup_name\fR .RS 4 The superuser can specify which group membership list to modify\&. .RE .PP \fB\-h\fR, \fB\-\-help\fR .RS 4 Display help message and exit\&. .RE .PP \fB\-l\fR, \fB\-\-list\fR .RS 4 List the group membership list\&. .RE .PP \fB\-p\fR, \fB\-\-purge\fR .RS 4 Purge all users from the group membership list\&. .sp If the /etc/gshadow file exist, and the group has no entry in the /etc/gshadow file, a new entry will be created\&. .RE .PP \fB\-R\fR, \fB\-\-root\fR\ \&\fICHROOT_DIR\fR .RS 4 Apply changes in the \fICHROOT_DIR\fR directory and use the configuration files from the \fICHROOT_DIR\fR directory\&. Only absolute paths are supported\&. .RE .SH "SETUP" .PP The \fBgroupmems\fR executable should be in mode 2710 as user \fIroot\fR and in group \fIgroups\fR\&. The system administrator can add users to group \fIgroups\fR to allow or disallow them using the \fBgroupmems\fR utility to manage their own group membership list\&. .sp .if n \{\ .RS 4 .\} .nf $ groupadd \-r groups $ chmod 2710 groupmems $ chown root:groups groupmems $ groupmems \-g groups \-a gk4 .fi .if n \{\ .RE .\} .SH "CONFIGURATION" .PP The following configuration variables in /etc/login\&.defs change the behavior of this tool: .PP \fBMAX_MEMBERS_PER_GROUP\fR (number) .RS 4 Maximum members per group entry\&. When the maximum is reached, a new group entry (line) is started in /etc/group (with the same name, same password, and same GID)\&. .sp The default value is 0, meaning that there are no limits in the number of members in a group\&. .sp This feature (split group) permits to limit the length of lines in the group file\&. This is useful to make sure that lines for NIS groups are not larger than 1024 characters\&. .sp If you need to enforce such limit, you can use 25\&. .sp Note: split groups may not be supported by all tools (even in the Shadow toolsuite)\&. You should not use this variable unless you really need it\&. .RE .SH "FILES" .PP /etc/group .RS 4 Group account information\&. .RE .PP /etc/gshadow .RS 4 secure group account information .RE .SH "SEE ALSO" .PP \fBchfn\fR(1), \fBchsh\fR(1), \fBpasswd\fR(1), \fBgroupadd\fR(8), \fBgroupdel\fR(8), \fBuseradd\fR(8), \fBuserdel\fR(8), \fBusermod\fR(8)\&.