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Can you change folder permissions in Linux?

青灯夜游
青灯夜游Original
2022-03-21 14:12:136596browse

Linux can change folder permissions. In Linux, you can use the chmod command to change the permissions of a folder (directory); this command can control the user's permissions on files or directories. The syntax is "chmod [who] [ |-|=] [mode] directory name" or " chmod permission value directory name".

Can you change folder permissions in Linux?

#The operating environment of this tutorial: linux5.9.8 system, Dell G3 computer.

Linux can change folder (directory) permissions.

In Linux systems, user settings file permissions control other users from accessing or modifying them. However, in system applications, sometimes you need to let other users use a file or directory that they cannot access originally. In this case, you need to reset the permissions of the file. The command used is the chmod command.

Linux chmod command: change directory permissions

Linux chmod (English full spelling: change mode) command is to control Commands for user permissions on files (directories).

Not everyone can change the access permissions of files and directories. Only the owners of files and directories have the permission to modify their permissions. In addition, super users can set permissions on all files or directories.

The chmod command is used as follows:

chmod [who] [+|-|=] [mode] 文件(目录)名

The operation object who in the chmod command can be any one of the letters in Table 1 or their combination.

Table 1: chmod command who option description
            Options           illustrate
u           Represents "user", the owner of the file or directory.
          g           Represents "group users", that is, all users with the same group ID as the file owner.
          o           Indicates "others users"
          a           Indicates "all users" and is the system default.

#chmod command operation symbol description is shown in Table 2.

Table 2: chmod command operation symbol description
          Options           illustrate
            Add a certain permission
          -             Cancel a permission
          =             Grants the given permission and removes all other permissions (if any)

mode 所表示的权限可以是表 3 中字母的任意组合。

        表 5:chmod 命令 mode 选项说明
                选项                 说明
                r                 可读
                w                 可写
                x                 可执行
                X                 只有目标文件对某些用户是可执行的或该目标文件是目录时才追加 x 属性
                s                 在文件执行时把进程的属主或组 ID 置为该文件的文件属主。方式“u+s”设置文件的用户 ID 位,“g+s”设置组 ID 位。
                t                 保存程序的文本到交换设备上
                u                 与文件属主拥有一样的权限
                g                 与和文件属主同组的用户拥有一样的权限
                o                 与其他用户拥有一样的权限  

在一个命令行中可给出多个权限方式,其间用逗号隔开。例如 chmod g+r,o+r example,这个命令将使同组和其他用户对文件 example 有读权限。

文件和目录的权限还可用八进制数字模式来表示。首先了解用数字表示的属性的含义:0 表示没有权限,1 表示可执行权限,2 表示可写权限,4 表示可读权限,然后将其相加。所以数字属性的格式应为 3 个从 0 到 7 的八进制数,其顺序是(u)(g)(o)。例如,如果想让某个文件的属主有“读/写”两种权限,需要把 4(可读)+2(可写)=6(读/写)。

使用数字修改文件权限的 chmod 命令基本格式为:

chmod [-R] 权限值 文件(目录)名;

-R(注意是大写)选项表示连同子目录中的所有文件,也都修改设定的权限。

例如,使用如下命令,即可完成对 .bashrc 目录文件的权限修改:

[root@localhost ~]# ls -al .bashrc
-rw-r--r--. 1 root root 176 Sep 22 2004 .bashrc
[root@localhost ~]# chmod 777 .bashrc
[root@localhost ~]# ls -al .bashrc
-rwxrwxrwx. 1 root root 176 Sep 22 2004 .bashrc

再举个例子,通常我们以 Vim 编辑 Shell 文件批处理文件后,文件权限通常是 rw-rw-r--(644),那么,如果要将该文件变成可执行文件,并且不让其他人修改此文件,则只需将此文件的权限该为 rwxr-xr-x(755)即可。

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