CODEWITHSUNDEEP
linuxbash
Unpossible
Unpossible

Reputation: 623

Best way to stop a bash script by ending processes

I am trying to setup a startup script where I can send "start" and "stop" commands to the processes that the script has started.

What I came up with kills the process(es) alright, but I think I will get in trouble for larger processes, and I also think there might be a better way of doing this:

pingcheck()
{
    ping -c2 "$1" &>/dev/null
    return "$?"
}

start()
{
    while :
    do
        if ! pingcheck "$our_ip"; then
            echo "$our_ip NOT online, WANTEDID >> $WANTEDID"
        else
            echo "$our_ip IS online, WANTEDID >> $WANTEDID"
        fi
    done 
}

stop()
{
    #Find the start process's id
    WANTEDID=$(ps aux | grep '[n]etworking.sh start' | awk '{print $2}' | head -n 1)
    #Kill it in a new processgroup
    setsid kill -9 "$WANTEDID"
    exit 0

}
trap "stop" SIGINT SIGTERM

case "$1" in
    start | stop ) "$1" ;;
esac

bash networking.sh start
192.168.20.5 IS online, WANTEDID >>
192.168.20.5 IS online, WANTEDID >>
192.168.20.5 IS online, WANTEDID >>
192.168.20.5 IS online, WANTEDID >>
192.168.20.5 IS online, WANTEDID >>
bash networking.sh stop
Killed

I would be grateful for any advice on how to write this better.

When I use SIGTERM, instead of -9 I get this in the screen and bash crashes (On ubuntu:

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ WANTEDID=26581 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ setsid kill -SIGTERM 26581 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ stop ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ps aux ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ awk '{print $2}' ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ grep '[n]etworking.sh start' ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ head -n 1 ^C+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ WANTEDID= +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ setsid kill -SIGTERM '' kill: failed to parse argument: '' +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ exit 0

Upvotes: 0

Views: 236

Answers (1)

Unpossible
Unpossible

Reputation: 623

Thanks to all the stellar advice I got here (@Aaron, @Kamil Cuk), the script now looks like this:

pingcheck()
{
    ping -c2 "$1" &>/dev/null
    return "$?"
}

start()
{
    while :
    do
        if ! pingcheck "$our_ip"; then
            ...do something...
            sleep 10s
        fi
    done 
}

stop()
{
    pkill -nf "$0 start"
    exit 0
}

case "$1" in
    start | stop ) "$1" ;;
esac

And it works fine. Thanks again everyone! I deeply appreciate all the help.

Upvotes: 1

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