How to change the read-only mode of a Linux hard drive?

To switch the Linux hard drive to read-only mode, you can follow these steps:

1. Open the terminal and log in as the root user or a user with sudo privileges.
2. List all disk partitions as root.
3. Unmount the /dev/sda device using sudo.
4. Please remount the /dev/sda device as read-only using the sudo mount command.
5. List all mounted partitions that are located on /dev/sda.

Please note that once the hard drive is switched to read-only mode, it will not be possible to write to it, only to read the data on the hard drive.