Provided by: passwd_4.1.4.1-1ubuntu2_i386 bug

НАЗВАНИЕ

       gpasswd - administer the /etc/group and /etc/gshadow files

СИНТАКСИС

       gpasswd [option] 

ОПИСАНИЕ

       The gpasswd command is used to administer /etc/group, and /etc/gshadow.
       Every group can have administrators, members and a password.

       System administrators can use the -A option to define group
       administrator(s) and the -M option to define members and has all rights
       of group administrators and members.

       gpasswd called by a group administrator with a group name only prompts
       for the new password of the group.

       If a password is set the members can still use newgrp(1) without a
       password, and non-members must supply the password.

   Замечания о паролях групп
       Пароли групп имеют врождённую проблему с безопасностью, так как пароль
       знает более одного человека. Однако, группы являются полезным
       инструментом совместной работы различных пользователей.

ПАРАМЕТРЫ

       Except for the -A and -M options, the options cannot be combined.

       The options which apply to the gpasswd command are:

       -a, --add user
           Add the user to the named group.

       -d, --delete user
           Remove the user from the named group.

       -r, --remove-password
           Remove the password from the named group. Only group members will
           be allowed to use newgrp to join the named group.

       -R, --restrict
           Restrict the access to the named group. Only group members will be
           allowed to use newgrp to join the named group.

       -A, --administrators user,...
           Set the list of administrative users.

       -M, --members user,...
           Set the list of group members.

ПРЕДОСТЕРЕЖЕНИЯ

       This tool only operates on the /etc/group and /etc/gshadow files.  Thus
       you cannot change any NIS or LDAP group. This must be performed on the
       corresponding server.

CONFIGURATION

       The following configuration variables in /etc/login.defs change the
       behavior of this tool:

       ENCRYPT_METHOD (string)
           This defines the system default encryption algorithm for encrypting
           passwords (if no algorithm are specified on the command line).

           It can take one of these values:

           o   DES (default)

           o   MD5

           o   SHA256

           o   SHA512

               Note: this parameter overrides the MD5_CRYPT_ENAB variable.

               Note: This only affect the generation of group passwords. The
               generation of user passwords is done by PAM and subject to the
               PAM configuration. It is recommended to set this variable
               consistently with the PAM configuration.

           MAX_MEMBERS_PER_GROUP (number)
               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).

               The default value is 0, meaning that there are no limits in the
               number of members in a group.

               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.

               If you need to enforce such limit, you can use 25.

               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.

           MD5_CRYPT_ENAB (boolean)
               Indicate if passwords must be encrypted using the MD5-based
               algorithm. If set to yes, new passwords will be encrypted using
               the MD5-based algorithm compatible with the one used by recent
               releases of FreeBSD. It supports passwords of unlimited length
               and longer salt strings. Set to no if you need to copy
               encrypted passwords to other systems which don't understand the
               new algorithm. Default is no.

               This variable is superceded by the ENCRYPT_METHOD variable or
               by any command line option used to configure the encryption
               algorithm.

               This variable is deprecated. You should use ENCRYPT_METHOD.

               Note: This only affect the generation of group passwords. The
               generation of user passwords is done by PAM and subject to the
               PAM configuration. It is recommended to set this variable
               consistently with the PAM configuration.

           SHA_CRYPT_MIN_ROUNDS (number), SHA_CRYPT_MAX_ROUNDS (number)
               When ENCRYPT_METHOD is set to SHA256 or SHA512, this defines
               the number of SHA rounds used by the encryption algorithm by
               default (when the number of rounds is not specified on the
               command line).

               With a lot of rounds, it is more difficult to brute forcing the
               password. But note also that more CPU resources will be needed
               to authenticate users.

               If not specified, the libc will choose the default number of
               rounds (5000).

               The values must be inside the 1000-999999999 range.

               If only one of the SHA_CRYPT_MIN_ROUNDS or SHA_CRYPT_MAX_ROUNDS
               values is set, then this value will be used.

               If SHA_CRYPT_MIN_ROUNDS > SHA_CRYPT_MAX_ROUNDS, the highest
               value will be used.

               Note: This only affect the generation of group passwords. The
               generation of user passwords is done by PAM and subject to the
               PAM configuration. It is recommended to set this variable
               consistently with the PAM configuration.

ФАЙЛЫ

       /etc/group
           содержит информацию о группах

       /etc/gshadow
           содержит защищаемую информацию о группах

СМОТРИТЕ ТАКЖЕ

       newgrp(1), groupadd(8), groupdel(8), groupmod(8), grpck(8), group(5),
       gshadow(5).