Question

I’m writing a script using multiple dialog screens in bash. One of the functions of the script should be killing specific processes. I load all my PID values in one array called pid:

pid = ('1234' '1233' '1232' '1231' '1230')

Then I present the user with a dialog checklist that contains a list of the processes.
After they select some of them dialog returns the checklist entry number, for example 0,2,4.

My initial plan was to store the selected entries in a second array and then use it to get specific PID’s from the first array, but so far, nothing I’ve tried worked, in this case that would be: 1234, 1232, 1230. So I can kill those specific processes.

Does anyone have a better solution? I want the easiest way of killing processes based on selections made by the user at the dialog checklist.

Here is the function in question:

stop_tunnel() {

local tunnels
local pid
declare -a tunnels
declare -a pid

#this is executed on a remote system in the real script
ps aux | grep -w ssh > $_temp

awk -F "ssh" '{print "ssh" $2}' $_temp > $_temp1
awk '{print $2}' $_temp > $_temp2

IFS='
'
tunnels=( $( < $_temp1 ) )
pid=( $( < $_temp2 ) )

dialog --checklist "Select tunnel to stop:" 10 72 0 \
                   0 "${tunnels[0]}" off \
                   1 "${tunnels[1]}" off \
                   2 "${tunnels[2]}" off \
                   3 "${tunnels[3]}" off \
                   4 "${tunnels[4]}" off \
                   2>$_temp

nr=$( < $_temp )

dialog --title " Tunnel stop " --msgbox "\nYou stopped these tunnels: ${nr[@]}" 6 44

}

The nr array holds the users selection. And I wanted to use that to pull specific members out of the pid array.

Answer 1

Select might be what you need:

select p in ${pid[@]} ; do   echo "kill" $p && break; done

Note that blanks around the assignment won’t work:

# wrong:
pid = ('1234' '1233' '1232' '1231' '1230')
# right:
pid=('1234' '1233' '1232' '1231' '1230')

To allow to kill multiple processes in sequence:

select p in ${pid[@]} ; do
  if [[ -n $p ]]
     then echo "kill" $p
     else break
  fi
done
1) 1234
2) 1233
3) 1232
4) 1231
5) 1230
#? 3
kill 1232
#? 4
kill 1231
#? 6

The echo is of course just for testing.

A hint for the user, that an invalid index will terminate the process killing seems appropriate. A second approach could be an explicit termination case:

pid=('1234' '1233' '1232' '1231' '1230' 'terminate')

which you would handle with the break.

If you just want to iterate over the selections, being made:

sel=(0 2 4) 
for n in ${sel[@]} ; do echo kill ${pid[$n]}; done  

update towards you comment:

I don’t have dialog installed, but I guess zenity is similar. There you capture the output of a list seleciton:

selection=($(zenity --list --text "kill something" --multiple --column "kill" --separator " " --checklist --column ps TRUE foo FALSE bar FALSE baz TRUE fozboa))