What is chmod 444 in Linux terminal?

In Linux, chmod is a command used to change file permissions. Each permission setting defines what actions users can perform on a file, such as reading, writing, or executing it. When you set a file to chmod 444, you’re applying a specific permission mode that makes the file read-only for everyone.

This means:

• The file owner can read it but cannot modify or delete it.

• Other users and groups can also read it but cannot change or execute it.

• It’s often used to protect critical files or configuration files from accidental modification.

To apply this permission, you would run:

chmod 444 filename

 chmod 444 sets the file permission to read-only for all users in Linux. This ensures that the file cannot be modified or executed, providing an extra layer of protection.