'\" t .\" Title: groupmod .\" Author: Julianne Frances Haugh .\" Generator: DocBook XSL Stylesheets vsnapshot .\" Date: 07/02/2024 .\" Manual: System Management Commands .\" Source: shadow-utils 4.16.0 .\" Language: English .\" .TH "GROUPMOD" "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" groupmod \- modify a group definition on the system .SH "SYNOPSIS" .HP \w'\fBgroupmod\fR\ 'u \fBgroupmod\fR [\fIoptions\fR] \fIGROUP\fR .SH "DESCRIPTION" .PP The \fBgroupmod\fR command modifies the definition of the specified \fIGROUP\fR by modifying the appropriate entry in the group database\&. .SH "OPTIONS" .PP The options which apply to the \fBgroupmod\fR command are: .PP \fB\-a\fR, \fB\-\-append\fR\ \&\fIGID\fR .RS 4 If group members are specified with \-U, append them to the existing member list, rather than replacing it\&. .RE .PP \fB\-g\fR, \fB\-\-gid\fR\ \&\fIGID\fR .RS 4 The group ID of the given \fIGROUP\fR will be changed to \fIGID\fR\&. .sp The value of \fIGID\fR must be a non\-negative decimal integer\&. This value must be unique, unless the \fB\-o\fR option is used\&. .sp Users who use the group as primary group will be updated to keep the group as their primary group\&. .sp Any files that have the old group ID and must continue to belong to \fIGROUP\fR, must have their group ID changed manually\&. .sp No checks will be performed with regard to the \fBGID_MIN\fR, \fBGID_MAX\fR, \fBSYS_GID_MIN\fR, or \fBSYS_GID_MAX\fR from /etc/login\&.defs\&. .RE .PP \fB\-h\fR, \fB\-\-help\fR .RS 4 Display help message and exit\&. .RE .PP \fB\-n\fR, \fB\-\-new\-name\fR\ \&\fINEW_GROUP\fR .RS 4 The name of the group will be changed from \fIGROUP\fR to \fINEW_GROUP\fR name\&. .RE .PP \fB\-o\fR, \fB\-\-non\-unique\fR .RS 4 When used with the \fB\-g\fR option, allow to change the group \fIGID\fR to a non\-unique value\&. .RE .PP \fB\-p\fR, \fB\-\-password\fR\ \&\fIPASSWORD\fR .RS 4 The encrypted password, as returned by \fBcrypt\fR(3)\&. .sp \fBNote:\fR This option is not recommended because the password (or encrypted password) will be visible by users listing the processes\&. .sp You should make sure the password respects the system\*(Aqs password policy\&. .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 .PP \fB\-P\fR, \fB\-\-prefix\fR\ \&\fIPREFIX_DIR\fR .RS 4 Apply changes in the \fIPREFIX_DIR\fR directory and use the configuration files from the \fIPREFIX_DIR\fR directory\&. This option does not chroot and is intended for preparing a cross\-compilation target\&. Some limitations: NIS and LDAP users/groups are not verified\&. PAM authentication is using the host files\&. No SELINUX support\&. .RE .PP \fB\-U\fR, \fB\-\-users\fR .RS 4 A list of usernames to add as members of the group\&. .sp The default behavior (if the \fB\-g\fR, \fB\-N\fR, and \fB\-U\fR options are not specified) is defined by the \fBUSERGROUPS_ENAB\fR variable in /etc/login\&.defs\&. .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 .PP /etc/login\&.defs .RS 4 Shadow password suite configuration\&. .RE .PP /etc/passwd .RS 4 User account information\&. .RE .SH "EXIT VALUES" .PP The \fBgroupmod\fR command exits with the following values: .PP \fI0\fR .RS 4 E_SUCCESS: success .RE .PP \fI2\fR .RS 4 E_USAGE: invalid command syntax .RE .PP \fI3\fR .RS 4 E_BAD_ARG: invalid argument to option .RE .PP \fI4\fR .RS 4 E_GID_IN_USE: group id already in use .RE .PP \fI6\fR .RS 4 E_NOTFOUND: specified group doesn\*(Aqt exist .RE .PP \fI9\fR .RS 4 E_NAME_IN_USE: group name already in use .RE .PP \fI10\fR .RS 4 E_GRP_UPDATE: can\*(Aqt update group file .RE .PP \fI11\fR .RS 4 E_CLEANUP_SERVICE: can\*(Aqt setup cleanup service .RE .PP \fI12\fR .RS 4 E_PAM_USERNAME: can\*(Aqt determine your username for use with pam .RE .PP \fI13\fR .RS 4 E_PAM_ERROR: pam returned an error, see syslog facility id groupmod for the PAM error message .RE .SH "SEE ALSO" .PP \fBchfn\fR(1), \fBchsh\fR(1), \fBpasswd\fR(1), \fBgpasswd\fR(8), \fBgroupadd\fR(8), \fBgroupdel\fR(8), \fBlogin.defs\fR(5), \fBuseradd\fR(8), \fBuserdel\fR(8), \fBusermod\fR(8)\&.