File Permissions Master Guide

Understanding permissions

-rwxr-xr--

• -: File type (- = file, d = directory)
• rwx: Owner permissions (read, write, execute)
• r-x: Group permissions
• r--: Others permissions

Give execute permission

chmod +x script.sh

Set specific permissions (755)

chmod 755 file.txt

• 7 (Owner): read + write + execute
• 5 (Group): read + execute
• 5 (Others): read + execute

Common permission codes

• 644: Read/write for owner, read-only for others
• 755: Executable for all, writable by owner
• 600: Private file, only owner can read/write
• 777: Full access for everyone (Avoid in production!)

Recursively change permissions

chmod -R 755 /var/www/html

Change file owner

chown username file.txt

Change owner and group

chown username:groupname file.txt

Recursively change ownership

chown -R www-data:www-data /var/www

View file permissions

ls -la file.txt

Set default permissions for new files

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