How to change permissions?

You can change file and directory permissions in Linux using the chmod command. Here are the common methods to do so:

1. Using Symbolic Notation:

You can specify permissions using letters:

• u: User (owner)
• g: Group
• o: Others
• a: All (user, group, and others)

You can add (+), remove (-), or set (=) permissions.

Examples:

• To add execute permission for the owner:

  chmod u+x filename
  

• To remove write permission for the group:

  chmod g-w filename
  

• To set read and write permissions for the owner and remove all permissions for others:

  chmod u=rw, o= filename
  

2. Using Numeric (Octal) Notation:

Permissions can also be set using numbers, where:

• 4: Read
• 2: Write
• 1: Execute

You combine these numbers for each user category (owner, group, others).

Examples:

• To set permissions to rwxr-xr-- (755):

  chmod 755 filename
  

• To set permissions to rw-r----- (640):

  chmod 640 filename
  

3. Recursively Changing Permissions:

To change permissions for a directory and all its contents, use the -R option:

chmod -R 755 directory_name

This command sets the permissions for the directory and all files and subdirectories within it.

If you have any further questions or need more examples, feel free to ask!