Linux file permissions
File permissions are stored together with the data on a disk. The Linux kernel uses them to decide which users and processes can access what file.
This page can be considered as a good cheat sheet, while the underlying articles explain how to use this information.
Main permissions
- Read (r): Allows users to view the contents of a file or directory
- Write (w): Grants users the ability to modify the contents of a file or directory
- Execute (x): Enables users to execute a file or access the contents of a directory
| Permission | Abbreviation | Octal value |
|---|---|---|
| Read | r | 4 |
| Write | w | 2 |
| Execute | x | 1 |
Possible combinations:
| Permissions | Octal Value |
|---|---|
| --- | 0 |
| --x | 1 |
| -w- | 2 |
| -wx | 3 |
| r-- | 4 |
| r-x | 5 |
| rw- | 6 |
| rwx | 7 |
Entities
- User (u): The user who owns the file or directory, or the owner of the file
- Group (g): A collection of users who share common permissions
- Others (o): Everyone else who is not the owner or a member of the group
How to change file permissions
Learn how to change the file permissions of files and directories on a Linux system. Follow the examples and make your system more secure.
Introduction in Linux file permissions
Learn the basics of how a Linux system applies file permissions. We look at examples to demystify the permissions mean and learn to troubleshoot common issues.
Set default file permissions on Linux with umask
Learn how to use umask to set the default file permissions in Linux. We look at examples, including how and where to implement them.
Relevant linux file permissions commands
Like to learn more about the commands used in this section? Have a look at the cheat sheets or the related command page.
- chmod
- ls