Group Management :
- A user can be participated to more than one group at the same time.
- A user who is member of a group can change to that group without password but a user NOT member can only change to that group if the group password exist and the user gives it.
- One of more users can become group administrators for specific groups.
- Group Administrators can:
1. add/change/delete the password of
the group
2. add/delete users to the group
3. reserve the group to members-only.
Types of
Group:
- Primary group: Every user must be a member of at least one group, which is identified by the numeric GID in /etc/passwd.
- Secondary group: A user may be listed as member of additional group in the relevant entries in the /etc/group.
- User private group: Created whenever a new user is added to the system and has the same name as the user for which it was created.
Example:
$ id
uid=501(linuxcare) gid=502(linuxcare) groups=502(linuxcare),506(rax)
Group
Management Commands:
- groupadd - adding group
# groupadd admin
# groupadd -r
admin //start
group id 101 and increase up to GID 499
# groupadd -g 600 admin
- groupmod - modifying group
# groupmod [-g new gid] [-n new name] group
# groupmod -g 600 -n networkcare linuxcare
- groupdel - deleting group
# groupdel networkcare
- gpasswd - administer /etc/group and /etc/gshadow
# gpasswd
networkcare
// making new password for networkcare
# gpasswd -A linuxcare
networkcare
// administrator for networkcare
# gpasswd -R
networkcare
// restrict non-members login
# gpasswd -r
networkcare
// delete group password
$ gpasswd -a linuxcare
networkcare
// adding new member
$ gpasswd -d linuxcare
networkcare
// deleting group member
- chgrp - Changes the group ownership of a file or directory.
# chgrp linuxcare /home/linuxcare
So In
this way group can be managed in Linux.
By Linux Care
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