# phpman > man > gpasswd(1) > **TLDR:** Administer `/etc/group` and `/etc/gshadow`. > - Define group administrators: `sudo gpasswd {{-A|--administrators}} {{user1,user2}} {{group}}` - Set the list of group members: `sudo gpasswd {{-M|--members}} {{user1,user2}} {{group}}` - Create a password for the named group: `gpasswd {{group}}` - Add a user to the named group: `gpasswd {{-a|--add}} {{user}} {{group}}` - Remove a user from the named group: `gpasswd {{-d|--delete}} {{user}} {{group}}` *Source: tldr-pages* --- [GPASSWD(1)](https://www.chedong.com/phpMan.php/man/GPASSWD/1/markdown) User Commands [GPASSWD(1)](https://www.chedong.com/phpMan.php/man/GPASSWD/1/markdown) ## NAME gpasswd - administer /etc/group and /etc/gshadow ## SYNOPSIS **gpasswd** [_option_] _group_ ## DESCRIPTION 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. They have 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)](https://www.chedong.com/phpMan.php/man/newgrp/1/markdown) without a password, and non-members must supply the password. ### Notes about group passwords Group passwords are an inherent security problem since more than one person is permitted to know the password. However, groups are a useful tool for permitting co-operation between different users. ## OPTIONS Except for the **-A** and **-M** options, the options cannot be combined. The options which apply to the **gpasswd** command are: ### -a --add Add the _user_ to the named _group_. ### -d --delete Remove the _user_ from the named _group_. ### -h --help Display help message and exit. ### -Q --root Apply changes in the _CHROOT_DIR_ directory and use the configuration files from the _CHROOT_DIR_ directory. ### -r --remove-password Remove the password from the named _group_. The group password will be empty. Only group members will be allowed to use **newgrp** to join the named _group_. ### -R --restrict Restrict the access to the named _group_. The group password is set to "!". Only group members with a password will be allowed to use **newgrp** to join the named _group_. ### -A --administrators Set the list of administrative users. ### -M --members Set the list of group members. ## CAVEATS 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: _DES_ (default), _MD5_, _SHA256_, _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 superseded 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 1000-999,999,999 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. ## FILES /etc/group Group account information. /etc/gshadow Secure group account information. ## SEE ALSO [**newgrp**(1)](https://www.chedong.com/phpMan.php/man/newgrp/1/markdown), [**groupadd**(8)](https://www.chedong.com/phpMan.php/man/groupadd/8/markdown), [**groupdel**(8)](https://www.chedong.com/phpMan.php/man/groupdel/8/markdown), [**groupmod**(8)](https://www.chedong.com/phpMan.php/man/groupmod/8/markdown), [**grpck**(8)](https://www.chedong.com/phpMan.php/man/grpck/8/markdown), [**group**(5)](https://www.chedong.com/phpMan.php/man/group/5/markdown), [**gshadow**(5)](https://www.chedong.com/phpMan.php/man/gshadow/5/markdown). shadow-utils 4.8.1 02/06/2024 [GPASSWD(1)](https://www.chedong.com/phpMan.php/man/GPASSWD/1/markdown)