I have mount webdav directory /mnt/wdav (more). And, now, I want to umount it. but i have following error:

umount: /mnt/wdav: target is busy (In some cases useful info about processes that use the device is found by lsof(8) or fuser(1).)

first step : find out processes using this mount

witr$ fuser -u /mnt/wdav /mnt/wdav: 408c(witr)

second step : identify process

witr$ ps 408 PID TTY STAT TIME COMMAND 408 pts/33 Ss 0:00 /opt/appli

third step : stop process

witr$ fuser -k /mnt/wdav

last step : safe umount

witr$ sudo umount /mnt/wdav