Create index.md for file-permissions (#24288)

* Create index.md for file-permissions

* corrected title syntax for contributor

guide/english/linux/file-permissions/index.md

@@ -0,0 +1,47 @@
+---
+title: File Permissions
+---
+
+# File Permissions
+
+* In Linux each file and directory has three user based permission groups:
+
+     **owner (u)**  - This group of permissions apply only on owner of directory or file, and they do not impact the actions of other users. 
+     
+     **group (g)** - This group of permissions apply only on group of user that are assigned to the directory or file, and they do not impact the actions of other users.
+     
+     **all users (o)** - This group of permissions apply to all users on the system.
+
+* In Linux each file and directory has three basic permission types:
+
+     **read** - This permission allows user to read content of files.
+     
+     **write** - This permission allows user to write or modify the file or directory.
+     
+     **execute** - This permission allows user to execute a file or view the content of directory.
+     
+* To view permission you can use some of content listing commands such as `ls -l`, `ll`  and etc.
+     
+     Permissions are displayed as **_rwxrwxrwx**. Where _ means it is either directory marked as `drwxrwxrwx` or link marked as `lrwxrwxrwx`, first set of rwx are permissions for owner, second one are for group and the last set of rwx permissions are applied on all users.
+     
+     Usually each set of permissions has its value in integer. You can calculate each set value if you sum default values of each permission.
+     
+     **read (r)** = **4**
+     
+     **erite (w)** = **2**
+     
+     **execute (x)** = **1**
+     
+     This is important when you want to grant permissions to some type of user `owner`, `group`, `all users`. Granting permissions is usually done with command `chmod`.
+     
+     ```
+     chmod u=rwx,g=rx,o=r myfile
+     ```
+     or equivalent
+     ```
+     chmod 754 myfile
+     ```
+     Example with no permission for groups
+     ```
+     chmod 704 myfile
+     ```