Linux User and Group management commands

Linux User and group management

Group Management

        groupadd命令：添加组        groupadd 选项  group_name           -g GID ：指定GID;默认是上一个组的GIDS+1           -r  创建系统组；        groupmod命令修改组属性        groupmod 选项 GROUP             -g 修改GID             -n 修改组名         groupdel：删除组         groupdel 组名  

User Management

          useradd命令 选项 登录名         -u,--uid：指定UID;         -g，--gid GROUP：指定基本组ID,此组得事先存在；         -G,--groups GROUP1 [,GROUP2,...]：指明用户所属的附加组，多个组之间有逗号分隔         -c，--comment COMMENT:指明注释信息；         -d，--home HOME_DIR：以指定的路径为用户的家目录：通过复制/etc/skel目录并重命名实现，如果指定的路径存在，则不会为用户复制环境配置文件；         -s,--shell SHELL：指定用户的默认shell,可用的所有shell列表存储在/etc/shells文件中；         -r，--system：创建系统用户；

 注意：创建用户时的诸多默认设定配置文件为/etc/login.defs useradd -D ：显示创建用户的默认配置： useradd -D 选项：修改默认选项的值； 修改的结果保存于/etc/default/useradd文件中；

• Modify a user's properties

  Usermod command: Modify user Properties
  usermod [Options] Login name
  -u,--uid UID: Modifying the UID of the user
  -G,--GID Group; Modify the user's base group
  -G,--groups Group: Modifies the additional group to which the user belongs: The original additional group will be overwritten;
  -A,--append: used in conjunction with-G to append new additional groups to the user;
  -c,--comment: Modify user's comment information;
  -d,--home Home_dir: Modify the user's home directory, the user's original files will not be transferred to the new directory;
  -m,--move-home: can only be used with the-D option to convert the original home directory to a new home directory;
  -l,--login new_login: Modify user Name
  -s,--shell Shell: Modifying the user's default shell
  -L,--Lock: Locks the user's password, which is added before the user's original password string!
  -U,--unlock: Unlock user password, coming soon! Delete
  Usedel command: Delete user
  Userdel [Options] Login userdel-r: Delete the user and delete their home directory;

• Modify Password command

  passwd command:
  (1) passwd: Modify the user's own password;
  (2) passwd USERNAME: Modify the password of the specified user, but only root has this permission;
  -l,-u: Locking and unlocking the user;
  -D: Clear the user password string;
  -e Date: Expiration period, date;
  -I days: inactivity period;
  -N days: The minimum period of use of the password;
  -X days: The maximum age of the password;
  -W days: Warning period;
  --stdin:echo "PASSWORD" | passwd--stdin USERNAME

• GPASSWD command:
  GPASSWD [options] Group name/etc/gshadow
  -a USERNAME: adding users to a group
  -D USERNAME: Removing users from a group
• NEWGRP command:
  Temporarily toggles the specified group into a basic group; NEWGRP-group name
  • Chage command:
    Change the password expiration information for a user
    Chage option Login name-d-e-w-m-M
  • ID Command:
    Displays the user's valid ID;
    -U: Displays only valid UID;
    -G: Displays only the user's base group ID;
    -G: Displays only the ID of the group to which the user belongs;
    -N: Displays only names, not IDs;
  • SU command: Switch user
    Logon switching: Re-initialized by reading the target user's configuration file
    Su-username
    Su-l USERNAME
    Non-logon switchover: Initialization of the target user's profile is not read
    Su Usernamehu
    Note: Administrators can switch to other users without a password;
    -C ' command ': The command specified here is only run as the specified user;
    Several other commands: Chsh,chfn,finger,whoami; PWCK;GRPCK, ""

Linux User and Group management commands