Lesson 5: Permissions & Ownership

Understanding Linux Permissions

Linux permissions control who can read, write, or execute files and directories. Proper permission management is critical for system security.

Permission Types

• Read (r) – view file contents
• Write (w) – modify files
• Execute (x) – run files or access directories

User Categories

• User (u) – file owner
• Group (g) – group members
• Others (o) – everyone else

Using chmod Command

• chmod 755 file – numeric permissions
• chmod u+x file – symbolic permissions
• chmod -R – recursive permission changes

File Ownership

• chown user file – change owner
• chown user:group file – change owner and group
• chgrp group file – change group ownership

sudo and Privilege Escalation

• sudo allows temporary admin access
• Controlled via /etc/sudoers
• Minimize root usage for security

Permissions in DevOps Scenarios

• Securing application configuration files
• Preventing unauthorized access
• Managing CI/CD agent permissions
• Hardening production servers