Groups Management

groupadd

• groupadd group_name - create new group group_name

groupdel

• groupdel group_name - delete group group_name

groupmod

• modify some group
• groupmod --new-name new_group_name group_name - rename group_name to new_group_name

/etc/group file

• contains the information related to the groups on the system
• format - group_name:password:gid:members

/etc/gshadow

• contains the information regarding the passwords for the groups
• format - group_name:password:group_administrator:group_members

gpasswd

• add new member to a group
• gpasswd -A member_name group_name
  • add member member_name to group group_name as group administrator
  • -A signifies group administrator
• usermod -aG group_name user_name
  • -a append
  • -G group
  • add user user_name to group group_name as a member
• usermod -a group_name user_name
  • add group_name group to the use user_name

power of group administrators

Suppose a user is group administrator of group1 then

• gpasswd -a user_name group1 - add user_name to group1
• getent group group1 - get the details of the group group1
• gpasswd -d user_name group1 - remove user_name from group1
• gpasswd group1 - set the password for the group1

newgrp

• temporarily add a group to your user
• newgrp grpname
• you will need group password for this