What is the difference between the -r and -l options in the umount command?

In Linux, the umount command is used to unmount a file system. The -r and -l are two options in the umount command, and they have the following differences:

1. Option -r:
2. The -r option signifies unmounting a file system by remounting it, which means if a directory or file system is still in use, it will first be remounted as read-only before attempting to unmount it.
3. When using the -r option, the umount command will attempt to forcefully unmount a file system, even if it is still in use.
4. For example, umount -r /mnt/data will attempt to unmount the /mnt/data directory in a “remount” manner.
5. Option “l”:
6. The “-l” option indicates performing a “lazy unmount,” which allows the system to continue using the file system until all references disappear, and then unmount it.
7. When the -l option is used, the umount command will return immediately without waiting for the file system to be completely unmounted.
8. For instance, using umount -l /mnt/data will unmount the /mnt/data directory in a lazy way.

In conclusion,

1. The -r option indicates remounting the file system in a way that attempts to forcibly unmount it, even if it is still in use.
2. The “-l” option allows for lazy unmounting, which enables the file system to remain in use until all references are gone before being unmounted.