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Background job not working as expected

 
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# 1  
Old 09-08-2014
Background job not working as expected
Hello Unix Buddies,


Code:
cat infinite.sh

#!/bin/sh
while true
do
      echo "Infinite loop"
done

I am running it in the background
Code:
$ ./infinite.sh > /dev/null &
[1] 31634

Then i do an exit or click on the cross mark to close the session.

Now my expectation is that when i open up a new session, the process should not be running.

But to my surprise if i do a grep , then i see that the process is still running. I did not expect this result for the background job. I thought that when we exit from the shell the background job dies.

Code:
$ ps -ef | grep infinite
root     30496     1 90 11:47 ?        00:00:39 /bin/sh ./infinite.sh
root     30578 30559  0 11:47 pts/0    00:00:00 grep infinite

I am using Linux.

Please through some light here.

Thanks,
Last edited by shellscripting; 09-08-2014 at 01:21 PM..
This User Gave Thanks to shellscripting For This Post:
Scrutinizer
# 2  
Old 09-08-2014
What is your system? What is your shell? I would have expected it to get killed too, along with everything else attached to that terminal.
# 3  
Old 09-08-2014
Below is the system information that i get
Code:
Shellscript:echo $SHELL
/bin/bash
Shellscript:uname -a
Linux was85host 2.6.27.45-0.1-vmi #1 SMP 2010-02-22 16:49:47 +0100 i686 i686 i386 GNU/Linux

# 4  
Old 09-08-2014
I completely agree with Coron688; everything should be killed.

First question is, How are you logging out? Are you using a terminal emulator? Is the interactive session also still running?
# 5  
Old 09-08-2014
When you put that job in the background, that job received the process id 31634.
In your ps output there is no pid 31634, so the job is gone.

The job with the pid 30496 must come from somewhere else...

Maybe you tested it from several terminals (which may be still active).
If this is the case, run following command in each terminal to detect background jobs: jobs
This User Gave Thanks to junior-helper For This Post:
Corona688
# 6  
Old 09-08-2014
I did the following test with bash:

Terminal 1:
Code:
$ while :; do sleep 1; done &
[1] 46950
$

Terminal 2:
Code:
$ shopt -s huponexit
$ while :; do sleep 1; done &
[1] 46988

Terminal 3:
Code:
$ ps -ef | grep -e 46950 -e 46988
  501 47102 43149   0  9:20PM ttys000    0:00.00 grep -e 46950 -e 46988
  501 46950 46940   0  9:19PM ttys001    0:00.03 -bash
  501 47100 46950   0  9:20PM ttys001    0:00.00 sleep 1
  501 46988 46944   0  9:19PM ttys002    0:00.02 -bash
  501 47099 46988   0  9:20PM ttys002    0:00.00 sleep 1

Terminal 1 & 2:
Code:
$ logout

[Process completed]

Terminal 3:
Code:
$ ps -ef | grep -e 46950 -e 46988
  501 46950     1   0  9:19PM ??         0:00.03 -bash
  501 47122 46950   0  9:20PM ??         0:00.00 sleep 1
  501 47124 43149   0  9:20PM ttys000    0:00.00 grep -e 46950 -e 46988

Last edited by Scrutinizer; 09-09-2014 at 01:55 PM..
These 3 Users Gave Thanks to Scrutinizer For This Post:
Corona688 junior-helper shellscripting
# 7  
Old 09-08-2014
Quote:
Originally Posted by Scrutinizer
I did the following test with bash ...:
Very interesting. I could reproduce this Smilie
I tested with simply closing the window, and it "worked" Smilie
 
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