Linux users are divided into three categories: 1. User management commands
Linux users are divided into three categories
1. User management commands (1) useradd—new user account
Sentence pattern
useradd (选项)用户名
Options
-ccommentAdd comments to new users
-dhome_dir specifies a name for the home directory (if you do not want to use the login name as the home directory name)
-eexpire_date specifies the date an account expires in YYYYY-MM-DD format
-finactive_days specifies the number of days after the account password expires that the account will be disabled; 0 means that the account will be disabled as soon as the password expires
Use -1 to disable this function
-ginitial_group specifies the GID or group name of the user login group
-Ggroup...Specify one or more additional groups to which the user belongs in addition to the login group
-k must be used together with -m. Is there a future for learning linux? Download the linux system image and copy the contents of the /etc/skel directory to the user's HOME directory
-mCreate the user's HOME directory
-M does not create the user's HOME directory (only used when creation is specified in the default settings linux sets user group permissions)
-nCreate a new group with the same name as the user's login name
-rCreate system account
-ppasswd specifies a default password for a user account
-sshell specifies the default login shell
-uuid specifies a unique UID for the account
Example—Create a new user zhangsan, the user group is net04
[root@localhost /]# useradd -g net04 zhangsan
(2) passwd—Set or change the user’s password and password attributes
Sentence pattern
passwd (选项)用户
Options
-kkeepnon-expiredauthenticationtokens
-lTurn off the account password. The effect is equivalent to usermod-L. Only root has the right to use this.
-uRecover account password. The effect is equivalent to usermod-Ulinux setting user group permissions, and only root has the right to use it.
-gChange the group password. Equivalent command of gpasswd.
-f Modifies the user information accessed by the finger command.
-d关掉使用者的密码认证功能,使用者在登陆时将可以不用输入密码,只有具备root权限的使用者方可使用.
-S显示指定使用者的密码认证种类,只有具备root权限的使用者方可使用.
实例—设置与更改属性
[root@localhost /]# passwd zhangsan
(3)usermod命令—修改用户的属性(超级用户可用)
句型
usermod (选项)用户名
选项
-c更改用户账号的备注文字。
-d登陆目录>更改用户登录时的目录。
-e更改账号的有效时限。
-f更改在密码过期后多少天即关掉该账号。
-g更改用户所属的群组。
-G更改用户所属的附加群组。
-l更改用户账号名称。
-L锁定用户密码,使密码无效。
-s更改用户登录后所使用的shell。
-u更改用户ID。
-U解除密码锁定
实例—将zhangsan改为zhangs
[root@localhost /]# usermod -l zhangs zhangsan
(4)userdel命令—删除指定的用户帐号(超级用户可用)
句型
userdel (选项)用户名
(5)su命令—切换用户身分
句型
su 用户名
(6)id命令—查看用户的UID、GID和用户所属用户组的信息
句型
id 用户名
(7)whoami命令—查看当前用户名
句型
whoami [--help][--version]
(8)w命令—查看当前登入系统用户和详尽信息二、用户组管理类命令(1)groupadd—新建组群(超级用户可用)
句型
groupadd (选项)用户组名
选项
-g:指定用户组ID
-o:准许组ID号不惟一(2)groupmod命令—修改指定用户组的属性(超级用户可用)
句型
groupmod (选项)用户组名
选项
-g:指定新的用户组ID
-n:指定新的用户组名子
-o:准许组ID号不惟一(3)groupdel命令—删除指定的用户组(超级用户可用)
句型
groupdel 用户组名
三、文件权限管理类命令(1)chmod命令—修改文件的访问权限
句型
chmod (模式)文件
模式
对象:u文件所有者、g同组用户、o其他用户
操作符:+降低、-删掉、=赋于
权限:r读、w写、x执行、s设置用户ID
实例—取消同组用户对file文件的写入权限
[root@localhost /]# chmod g-w file
将pict目录的访问权限设置为775
[root@localhost /]# chmod 775 pict
(2)chown命令—将指定文件的拥有者改为指定的用户或用户组
句型
chown (选项)(所有者/组) 文件
(3)chgrp命令—改变文件的所属用户组
句型
chgrp(选项)(组)文件
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