To bind or remount part of the file hierarchy at another directory in Linux, you can use the mount command with the --bind option.
Here is the syntax for using the mount command with the --bind option:
mount --bind <source> <destination>
Replace <source> with the path to the source directory and <destination> with the path to the destination directory.
For example, to bind the /var/www directory to the /var/www-copy directory, run the following command:
mount --bind /var/www /var/www-copy
This will create a bind mount of the /var/www directory at the /var/www-copy directory. Any changes made to the files in the /var/www directory will be reflected in the /var/www-copy directory, and vice versa.
To remount a bind mount, use the --bind option along with the --remount option. For example, to remount the /var/www bind mount at the /var/www-copy directory, run the following command:
mount --bind --remount /var/www /var/www-copy
That's it! You now know how to bind or remount part of the file hierarchy at another directory in Linux using the mount command.