[SOLVED] bash script how kill app running in bg that was started by the script

porphyry5 · 07-26-2014, 12:01 PM

If I start an app running in a bash script, I have to start it in bg in order for the script to continue processing. After a certain time I want the script to terminate that app gracefully, but I find that neither kill nor kill -9 issued in the script has any effect on that app. How then can I do it?
Here is the script

Code:

~ $ declare -f nt
nt ()
{
    while [ 0 ]; do
        y=$(date +%H%M);
        w=($(ps ax|grep rtorrent|grep -v grep));
        if [[ "${w[4]}" != "rtorrent" ]]; then
            rtorrent & echo "$(ps ax|grep rtorrent|grep -v grep) started $(date)";
            sleep 30;
        fi;
        if [[ "$(date +%H%M)" > "$y" ]]; then
            if [[ "${w[4]}" == "rtorrent" ]]; then
                kill -9 ${w[0]} && echo "${w[0]} killed $(date)";
            fi;
        fi;
        sleep 30;
    done
}

And here is what happens when I run it

Code:

~ $ nt
[1] 20101
20101 pts/4    D      0:00 rtorrent started Sat Jul 26 09:31:26 PDT 2014

[1]+  Stopped                 rtorrent

The system claims that the kill -9 has taken effect, but notice that the '&& echo ...' tied to its successful completion does not show. After 2 minutes I do

Code:

^C
~ $ ps ax|grep rtorrent|grep -v grep
20101 pts/4    Tl     0:00 rtorrent
~ $ kill 20101 && sleep 0.1
~ $ ps ax|grep rtorrent|grep -v grep
20101 pts/4    Tl     0:00 rtorrent
~ $ sleep 60
~ $ ps ax|grep rtorrent|grep -v grep
20101 pts/4    Tl     0:00 rtorrent
~ $ kill -9 20101
~ $ ps ax|grep rtorrent|grep -v grep
[1]+  Killed                  rtorrent
~

Finally I get rid of it with kill -9 from the tty. Why does it work there but not in the script? How can I terminate rtorrent gracefully in the script?

firstfire · 07-26-2014, 12:43 PM

Hi.

IMHO:
Instead of

Code:

while [ 0 ]; ...

I'd prefer

Code:

while :; ...

Instead of

Code:

grep rtorrent | grep -v grep

one may use

Code:

grep [r]torrent

Now, go back to kill (not literally

): it looks like this condition

Code:

[[ "$(date +%H%M)" > "$y" ]];

is never true because the value of $y is the same as $(data +%H%M).

porphyry5 · 07-26-2014, 01:18 PM

Quote:

Originally Posted by firstfire

Now, go back to kill (not literally

): it looks like this condition

Code:

[[ "$(date +%H%M)" > "$y" ]];

is never true because the value of $y is the same as $(data +%H%M).

This is true, thank you