Group Management Linux Each user must belong to a group and cannot be independent from outside the group

Group Management

Each Linux user must belong to a group and cannot be independent from the group. Similarly to the Linux input method, each file in Linux will have the concepts of owner, group, and other groups.

The original creator of the file is the owner of the file, and the owner information can be viewed through ls-lha.

<code class="hljs markdown vditor-linenumber" style="max-height:1000px">chown 命令用途更改与文件关联的所有者或组。
<span class="hljs-bullet"> -<span> chown 用户名 文件名
<span class="hljs-section"> -R 递归目录下的子文件及目录
------------------------------------<span>
chgrp 变更文件或目录的所属群组
<span class="hljs-bullet"> -<span> chgrp 组名 文件名
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Except for the owner of the file and the users in its group, all other users of the system are other groups of the file.

When adding a userLinux sets user group permissions. You can specify which group to add the user to. You can also use root management permissions to change the group of a user.

<code style="max-height:1000px" class="hljs markdown vditor-linenumber">usermod -g 组名 用户名
<span class="hljs-section">usermod -d 目录名 用户名 # 用于改变用户登录的初始目录
-----------------------------------------------<span>
cat /etc/group | grep manager # 只过滤manager的组
<span class="hljs-code">-i：忽略大小写进行匹配。
-v：反向查找，只打印不匹配的行。
-n：显示匹配行的行号。
-r：递归查找子目录中的文件。
-l：只打印匹配的文件名。
-c：只打印匹配的行数。
------------------------------------------------
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File permissions rwxFile permissions

<code style="max-height:1000px" class="hljs pgsql vditor-linenumber">[<span class="hljs-keyword">admin<span>@centos7 ~]$ ll
总用量 <span class="hljs-number">8<span>
drwxrwxr-x. <span class="hljs-number">2<span> <span class="hljs-keyword">admin<span> <span class="hljs-keyword">admin<span> <span class="hljs-number">6<span> <span class="hljs-number">4<span>月 <span class="hljs-number">5<span> <span class="hljs-number">10<span>:<span class="hljs-number">36<span> Downloads
<span class="hljs-comment">----------------------------------<span>
r(<span class="hljs-number">4<span>)<span class="hljs-comment">--- >read<span>
 - 可读取文件内容，可查看目录内容
w(<span class="hljs-number">2<span>)<span class="hljs-comment">--- >write<span>
 - 可写，包含创建、删除及重命名目录
x(<span class="hljs-number">1<span>)<span class="hljs-comment">--- >execute<span>
 - 可执行文件，可进入目录
<span class="hljs-comment">----------------------------------<span>
chmod <span class="hljs-number">777<span># 修改为可读可写可执行，<span class="hljs-keyword">User<span> <span class="hljs-keyword">Group<span> Other
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w means writable permission. When this permission is applied to a file, it does not mean that the file can be deleted. The prerequisite for deleting the permission of the file is that the directory where the file is located has write permission, and the file can be deleted. .

0-9 digit description:

1. Bit 0 determines the file type (d,-,1,c,b)

l is a link, which is equivalent to the shortcut method of Windows

d is the directory linux sets user group permissions, equivalent to the windows folder

c is the line device file, keyboard, mouse, ls-l/dev/

b is a block device, such as a hard disk, ls-l/dev/

2. Positions 1-3 determine that the owner (the owner of the file) has the permissions of the file---User

3. Positions 4-6 determine that the group to which it belongs (same as the user group) has the permissions for the file ---Group

4. Positions 7-9 determine that other users have permissions to the file ---Other

chmod change permissions

You can change the permissions of files or directories through chmod.

u:Owner

g:All groups

o:Others

a:Everyone

<code style="max-height:1000px" class="hljs perl vditor-linenumber"><span class="hljs-number">1<span>)<span class="hljs-keyword">chmod<span> u=rwx,g=rx,o=<span class="hljs-keyword">x<span> 文件名/目录名
<span class="hljs-keyword">chmod<span> <span class="hljs-number">761<span> 文件名/目录名
<span class="hljs-number">2<span>)<span class="hljs-keyword">chmod<span> o+w 文件名/目录名<span class="hljs-comment"># 给other其他用户赋w权限<span>
<span class="hljs-number">3<span>)<span class="hljs-keyword">chmod<span> a-<span class="hljs-keyword">x<span> 文件名/目录名<span class="hljs-comment"># 给all全部用户的x权限去掉<span>
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