Question

For stopping activity in my embedded Linux system, I have the following shell script (interpreted by busybox):

#!/bin/sh
pkill usefulp_program
swapoff /home/.swapfile
umount -l /home
sleep 3 # While I can't find a way to sync, sleep

If I take off the sleep line, the script returns immediately, without waiting even for the umount (which is lazy, as for some reason it refuses to unmount otherwise). Do you know how can I wait for all the three operations to complete before finishing the script? Resorting to an arbitrary sleep does not look like a good solution.

Also, any hint on why I can not umount without the -l?

Answer 1

You need to wait for the killed process to terminate. As per your comment…

wait <pid>

…doesn’t work! So, could loop ala:

while ps -p <pid> > /dev/null; do sleep 1; done

to wait for the killed process to terminate before doing the swapoff and umount.