Permission Basics
Understanding File Permissions in Linux
File permissions are a critical aspect of system security and access control in Linux systems. In the context of Git and filesystem management, understanding these permissions is essential for maintaining proper access and collaboration.
Permission Types
Linux uses a three-tier permission system for files and directories:
Permission |
Symbol |
Numeric Value |
Meaning |
Read |
r |
4 |
View file contents or list directory |
Write |
w |
2 |
Modify file or create/delete files in directory |
Execute |
x |
1 |
Run file or access directory |
Permission Levels
Permissions are set for three user levels:
- Owner (User)
- Group
- Others
Viewing Permissions
Use the ls -l
command to view file permissions:
$ ls -l example.txt
-rw-r--r-- 1 user group 1024 May 10 10:30 example.txt
Permission Representation
graph TD
A[Permission Representation] --> B[User/Owner Permissions]
A --> C[Group Permissions]
A --> D[Other Permissions]
B --> E[Read r]
B --> F[Write w]
B --> G[Execute x]
C --> H[Read r]
C --> I[Write w]
C --> J[Execute x]
D --> K[Read r]
D --> L[Write w]
D --> M[Execute x]
Changing Permissions
Use chmod
to modify file permissions:
## Add execute permission for the owner
$ chmod u+x script.sh
## Remove write permission for group
$ chmod g-w document.txt
## Set full permissions for owner, read/execute for group and others
$ chmod 755 script.sh
Best Practices
- Follow the principle of least privilege
- Regularly audit file permissions
- Use group permissions for collaborative projects
- Be cautious when modifying system file permissions
LabEx Tip
When working with Git repositories, understanding filesystem permissions is crucial for smooth collaboration and secure code management. LabEx recommends always verifying permissions before sharing or modifying project files.