# umount /dev/sda2

umount: /: target is busy.

perhaps

umount: /dev/sda2: device is busy

This is because some users are using files on the current disk. There are two solutions:

① Force uninstall (not recommended)

umount -l /dev/sda2

② After confirming with the user, close the processes related to these open files

see:

lsof /dev/sda2

Kill program:

lsof /dev/sda2 | awk ‘{print $2}’ | xargs kill -9

Uninstall:

umount /dev/sda2