I have a strange issue, I can't quite get my head around. What I do is run a function called fn_rundumper which basically just calls the bash code:
pterm -z "cmd.sh" param1 &
Here is the output of that, which includes the background pid "27938858":
fn_rundumper
running fn_dumper...
[1] 27938858
fn_dumper...done
Then I look at the job numbers that are running this also shows PID "27938858":
jobs -l
[1] + 27938858 Running $(pterm -z "$SCRIPTS_DIR/run_dumper.sh" $VO
Then I do a ps command to see what pterms are running:
ps | grep pterm
24285189 ? 00:00:00 pterm
27938859 ? 00:00:00 pterm
This yields the PID 27938859. This is different to the others!
When I kill PID 27938858 nothing seems to happen. When I kill PID 27938859 then the background pterm is closed.
The problem is that I may want to run many different background pterms as well as some pterms that are not opened as background tasks (i.e. run separately). So when I come to tidy up I just want to close the pterms that I have opened via my script.
I was trying to use jobs -l to see the PIDs I need to close, but as I just described this is the wrong PID.
Can anyone explain why this happens? and also what I need to do to get the correct PID? Thanks!
- Edit1 -
The best I can think of is to do a ps | grep pterm before and after and compare the results to find the new pterm PID... do-able, but ugly :(
- Edit2 -
I tested this again on the command line (no function call):
First I did:
`pterm -z "$VOE_SCRIPTS_DIR/run_dumper.sh" $PROJECT_DIR` &
And then looked at the ps / $! results and got the same behavior.
Then I did:
pterm -z "$VOE_SCRIPTS_DIR/run_dumper.sh" $VOE_PROJECT_DIR &
i.e. removed the back-ticks, now the PIDs all match up! I think I can remove the back-ticks from my code, but I don't really understand what that is all about!
Using $() or backticks (command substitution) creates a subshell. So 27938858 is the PID of a subshell which in turn inkokes pterm with PID 27938859.
Command substitution seems useless in your example, so you should just remove it.