How to create a user and specify a user group in Linux

linuxCreate a user and specify a user group

1. View all users

cat /etc/passwd

##Every The first line is the username.

About uid: 0 represents the administrator (root), 1 - 500 represents the system user, 501 - 65535 represents the ordinary user

cat /etc/group is used to view all user groups. Similar to viewing users

2. Add users

groupadd zhangsangroup   #创建用户组zhangsangroup
useradd -g zhangsan zhangsan  创建用户zhangsan并加入zhangsangroup组

useradd parameters:

• -u UID: Specify UID, this UID must be greater than or equal to 500, and there is no UID occupied by other users

• -g GID/GROUPNAME: Specify the default group, which can be GID or GROUPNAME, and must also exist

• -G GROUPS: Specify additional groups

• -c COMMENT: Specify the user’s comment information

• -d PATH: Specify the user’s home directory

3. Modify user password

passwd zhangsan

4. Related commands

1. Other user operation commands

useradd  user3  #新增用户
usermod –l u1 user1  #将用户user1的登录名改为u1
usermod –d /users/us1 user1   #将用户 user1家目录改为/users/us1
usermod –g users user1 #将用户user1加入到 users组中，
userdel user3  #删除用户
userdel –r user3  #删除用户并删除家目录
groupadd users #添加一个用户组users
groupmod –n user users    #修改组名user为users
groupdel users    删除组users

# The

• ##id

  command can view the UID and GID of a user, for example: id user4

• finger

  command can view the user’s main Directory, startup shell, user name, address, phone number and other information. Example: finger user4

##groups
• command to view the groups to which the user belongs, for example: groups root
  2. Use the gpasswd command to add users to the group.

Only root and group administrators can change the members of the group:

gpasswd –a user1 users  #把 user1加入users组
gpasswd –d user1 users #把 user1退出users组

3. Modify file permissions chmod

chmod -R 777 /var/lib/mysql   #表示修改文件为最高权限

-R means processing all files in the specified directory and its subdirectories

4. Modify the user and group chown of the file (note: the owner is first, the group is last)

chown -R mysql:mysql /var/lib/mysql

Format: chown [option]...[owner][:[group]] File...

-R means to process all files in the specified directory and its subdirectories

linuxCreate a user and determine the group the user belongs to

1. Create the group monster

[root@zhz home]# groupadd monster

2. Create the user tom, and the group tom belongs to is monster

[root@zhz home]# useradd -g monster tom

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