Centos User Group management

# Group account management linux group management =-= -= 1. classification private group: only one user can be included (automatically created by the created user) Standard Group: can contain multiple users 2. information group name of the group: GID of the group: a member of the group's unique identifier password group 3. manage group files/# manage group accounts


Linux group management
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1. group classification
Private group: only one user can be included (automatically created by the created user)
Standard Group: can contain multiple users


2. group information
Group name: group identifier
GID: a member of the password group with the unique identifier of the group.


3. group management
File/etc/group function:
System Group Information: g1: x: 500: u1, u2, u3


4. group account management tools


1) create a group
Format: groupadd [parameter] group name
Parameters:
-G GID: specifies the value of GID.
-R: create a system user group


Instance:
1) # groupadd g2
2) # groupadd? R g3
Create a system group. A system group is an entry with an GID between SYSTEM_GID_MIN and SYSTEM_GID_MAX
Defined in/etc/login. defs, if no GID is specified.


2) delete a group
Format: guoupdel group name
Instance: guoupdel G3


3) modify group information
Format: groupmod [parameter] group name
Parameters:
-N New Group name: modify the GID of the group
-G GID: modify the GID of the group.
-A username: add A user to the group
-R username: delete a user's slave group
Instance:
1) # groudmod-n group g1
2) # groupmod-g 860 u1, u2


4) change the password
Format: gpasswd [parameter] group name
Parameters:
-A user name: add users to a specified group
-D user name: delete a user instance from a specified group:
1) # gpasswd-a u1 root
2) # gpasswd-d u1 root


5) display the user group
Format: groups [user name]
Instance:
1) # groups (display the group to which the current user belongs)
2) # groups root (display the Group of the root user)




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Instance: groupadd [-r] groupname


-R option: create a system Group


1. create a user group tata
Groupadd tata


2. create a group with the initial password tata
Groupadd-p $ (openssl passwd-1-salt "tata" tata) tata


3. change the group password
Root @ OP_39_184_sles10:/usr # gpasswd tata
Changing the password for group tata.
New Password:
Re-enter new password:
Password changed.


4. add the user tata to the group tata
Root @ OP_39_184_sles10:/usr # groupmod-A tata
Root @ OP_39_184_sles10:/usr # id tata
Uid = 1005 (tata) gid = 100 (users) groups = 100 (users), 1005 (tata)


5. delete user tata to group tata
Root @ OP_39_184_sles10:/usr # groupmod-R tata
Root @ OP_39_184_sles10:/usr # id tata
Uid = 1005 (tata) gid = 100 (users) groups = 100 (users)




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Tools or commands used to manage user groups;
Groupadd note: add a user group;
Gpasswd note: set the group password. this setting group password is generally called after a new group is created.
Groupdel note: delete a user group;
Groupmod note: modify user group information
Groups note: displays the user group to which the user belongs.
Grpck
Note: Use the/etc/group and/etc/gshadow file content to synchronize or create/etc/gshadow. if/etc/gshadow does not exist, create it;
Grpunconv note: use the/etc/group and/etc/gshadow file content to synchronize or create/etc/group, and then delete the gshadow file;