I usually start a download before I go to school.
Which command should I use to automatically make the necessary saves and turn off the computer after a particular task has been completed?
(Say, after installing the updates, or after downloading a large file.)
I have also cross-posted at askubuntu.
It depends you started task. If it is some command line tool you could simply run halt or shutdown -h now:
wget http://..../somelargefile; halt - halt will be executed after wget
wget http://..../somelargefile && halt - halt will be executed if wget return no errors
wget http://..../somelargefile || halt - halt will be executed if wget return errors
Alternative to this is using kshutdown - in this app you can specify what action should be done (reboot/shutdown/hibernate/etc or command execution) and when (after some time or when another application exits). If you want to use this tool you need to chose correct process - some update utilities starts few subprocesses.
shutdown a time to wait; no need to use kshutdown for that purpose. shutdown doesn't have any way of waiting for an actual event. Every process has a directory named according to its process id (pid) in the proc filesystem. Therefore you can wait for a specific process' termination by checking whether its directory exists repeatedly.
You can use this to perform a system shutdown after process termination like this (replace 2296 by the pid to wait for):
su -c 'while [[ -d /proc/2296 ]]; do sleep 1; done; poweroff' Advantages:
sudo-password prompt).Disadvantages:
ps in that same terminal should help you spot the PID for the CMD. If the process was/is in another terminal pipping the ps output for everything through grep to filter for your command should help you find it ps -elf | grep <command_related_word> pgrep aka process grep... If you want to monitor an already started process, you can do this in a shell :
# while pgrep &>/dev/null -f process_name; do sleep 60; done; shutdown -h now You can use the && and || operators to chain commands together. For example:
apt-get update && sleep 2 && init 0 which will perform an update to the system using aptitude, wait 2 seconds, and go to runlevel 0, depending on your system this may or may not actually power off the hardware.
To speak to one or more operations following a more arbitrary operation, such as a, presumably web browser, download you would require additional logic to watch the downloading file to verify that the download has in fact completed, however, the shell logic is unchanged.
There is a application, named sentinella which can do it for you with its GUI: 
for installing it:
sudo aptitude update sudo aptitude install sentinella I had the same problem with download (in Firefox) and backup. I solved it by starting another, parallel bash script. It monitors network traffics. When it is low for some period of time, it will suspend/shutdown the computer.
The heart of the script:
ip -s link show dev wlan0 # This gets transffered bytes on wifi. ip -s link show dev wlan0 | sed -n '4p;6p' | awk '{ print $1 }' | paste -sd+ | bc # This combines all the traffic together. So the core function:
function statistics { # $1=network $2=seconds first=$(ip -s link show dev $1 | sed -n '4p;6p' | awk '{ print $1 }' | paste -sd+ | bc) sleep $2 second=$(ip -s link show dev $1 | sed -n '4p;6p' | awk '{ print $1 }'| paste -sd+ | bc) echo $(( (1 + $second - $first) / $2 )) # simple averadge return 0 } while (true); do if [ $(statistics wlan0 300) -lt 100000 ]; then sudo pm-suspend # but you must put pm-suspend in "sudo visudo". Say as UserIsMarchingSchool ALL=NOPASSWD: /usr/sbin/pm-suspend fi done Well, a bit crazy, but independent from the original program. May it help you as an hint. I suppose it can be solved in a simpler way. :-)
