Unable to find a shell script that runs in the background via pgrep or ps -grep

Question

I have a file named toto.sh and the content of the file is:

#!/bin/sh
for i in $(seq 1 100); 
do
   echo "CREATE TABLE test_$i (id NUMBER NOT NULL);
   ! sleep 10
   select * from test_$i;
   ! sleep 10
   DROP TABLE test_$i;" | sqlplus system/mypassword &
done

I execute the bash script:

./toto.sh

Now i am trying to search the process like so:

pgrep -f toto.sh
ps -ef | grep toto.sh
ps aux | grep toto.sh

And i am getting no relevant results:

root     24494 15043  0 10:47 pts/5    00:00:00 grep toto.sh

However, I can see via pgrep etc. the sleep and sqlplus processes fired up through the script,

What am i doing wrong here?

The script probably dies leaving sqlplus instances orphaned before you run pgrep — oguz ismail, Nov 19 '19 at 08:58
How come the script dies while it sleeps? we use longer sleeps and still the same problem — totothegreat, Nov 19 '19 at 08:59
echo exits after echoing, toto.sh exits after sending 100 processes to the background, only sqlpluses stay alive since they sleep — oguz ismail, Nov 19 '19 at 09:01
I mean, sqlplus is indeed run in a subshell, but the subshell replaces itself with sqlplus through an exec*() call, so it becomes a sqlplus instance — oguz ismail, Nov 19 '19 at 09:05
What do you mean kill? It's already dead the moment you run it — oguz ismail, Nov 19 '19 at 09:08
I meant killing everything toto.sh fired up, without killing other sleeps, other sqlplus instances on the same machine — totothegreat, Nov 19 '19 at 09:09
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/202627/discussion-between-totothegreat-and-oguz-ismail). — totothegreat, Nov 19 '19 at 09:13
To kill sqlplus processes: `echo ... | sqlplus system/mypassword & echo $! >>pids.txt`. Later: `kill $( — anishsane, Nov 19 '19 at 09:13
I don't know. Maybe toto.sh should first set a trap like `trap 'kill -KILL 0' EXIT` and then `wait` for childs to die? So you will be able to hit Ctrl-C and kill the whole family — oguz ismail, Nov 19 '19 at 09:17

score 3 · Accepted Answer · answered Nov 19 '19 at 09:24

3

When you want toto.sh to show up, make it stay active. End the script with wait, waiting for all children.

#!/bin/bash
for i in $(seq 1 100); 
do
   echo "CREATE TABLE test_$i (id NUMBER NOT NULL);
   ! sleep 10
   select * from test_$i;
   ! sleep 10
   DROP TABLE test_$i;" | sqlplus system/mypassword &
done
wait

An alternative would be adding a sleep command in the loop (I sleep 1 second after 10 iterations):

#!/bin/bash
for i in $(seq 1 100); 
do
   echo "CREATE TABLE test_$i (id NUMBER NOT NULL);
   ! sleep 10
   select * from test_$i;
   ! sleep 10
   DROP TABLE test_$i;" | sqlplus system/mypassword &
   ((i%10==0)) && { echo "i=$i"; sleep 1; }
done

answered Nov 19 '19 at 09:24

Walter A

19,067
2
23
43

But, this way `sleep`s won't die even though `toto.sh` is killed – oguz ismail Nov 19 '19 at 09:51
@oguzismail Killing the porcess was not part of the question. I would remove the sleep commands `sqlplus`, they are not needed for the database. The script is an example, creating and deleting the table has no functional result. – Walter A Nov 19 '19 at 10:00
1

Oh, okay then, I didn't realize that – oguz ismail Nov 19 '19 at 10:01

Unable to find a shell script that runs in the background via pgrep or ps -grep

1 Answers1