Chmod File Permissions in Linux/Unix

Linux is derived from UNIX and they are a lot of Linux distributions in the market, which can be accessed by many users continuously. Most of the servers provider recommend the Linux operating system by using this you have some security problems for files and folder permission. So Linux providing various kind of file permission that accessed by user or group. For effective security Linux providing two authorization levels.

1. Ownership
2. Permission

If you like to generate permission quickly, Here you have Chmod Unix Permissions Calculator. Using this you can generate your Octal or Symbolic value.

Unix/Linux Ownership

For your file and folder on Unix/Linux system, they are 3 types of ownership there, the types are listed below.

User

The person who created file or folder they become its owner. So some times the user also called as owner.

Group

In the User Group, you have multiple users in the group. All the users having the same permission for every folder and file. If you have a project file that files need to access means you can assign read and write permission for the entire group. This permission only access by group members and no one else can modify the file or folder.

Other

Other, all can access the file. The file may be created by you or you belong to a User Group who have access to give the file and folder.

Unix/Linux Permissions

In your file and folder in Unix/Linux, you have the following 3 permission.

Read

This read permission gives the authority to open and read the files.

Write

Using write permission you have access to edit or modify the contents of the file.

Execute

Using Windows operating system it is easy to run “.exe” extension but in Unix/Linux you can’t run a program unless the execute permission is set.

Below the characters are very easy to remember.

Read Permission r
Write Permission w
Execute Permission x
No Permission -

Changing File or Folder permissions with 'chmod' command

Change mode is shortly known as chmod you can change the permissions like (read, write, execute) on your file or folder for the owner and group. Based on the following syntax you change the file permission.

Below you can see all the permission types

Number	Symbol	Permission Type
0	---	No Permission
1	--x	Execute
2	-w-	Write
3	-wx	Execute + Write
4	r--	Read
5	r-x	Read + Execute
6	rw-	Read +Write
7	rwx	Read + Write +Execute

Below you can see the chmod command examples

Owner can read and write

Owner can read, write and execute

Everyone can read and write

Everyone can read, write and execute

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