Running process in background after closing termin

Question

I am trying to run a script in the background even after closing the terminal. I have searched and searched and tried nohup and disown but neither seem to be working. When I close a terminal window, I get the typical Closing this window will terminate the running processes: watch. message. That ends up terminating my background process, even when using nohup or disown. What could be the problem?

My code is a simple two lines

cmd="nohup watch -n 1 sudo /etc/block.sh > /dev/null"
$cmd & # blocks automatically  

It is located in .bash_profile, because I want it to start up whenever I open a new terminal.

You can ignore the sudo; I've already found a way to execute a sudo command without entering the password.

I am using Mac OSX.

Answer 1

This is already answered, but the Screen utility seems like it would be perfect for this.

• man screen To view the documentation for screen.

• www.ss64.com/osx/screen.html to view slightly more user friendly documentation.

• Start screen with a name and a script to run:

  screen -S GWatch Scripts/gw_watch.sh
  This starts a screen session named 'GWatch' and executes gw_watch.sh.
  

When a screen session is started, one has the option of disconnecting from it. This will leave the screen active in the background. It will remain active even after the user logs out (permissions notwithstanding).

Here is an example:

1. Create a shell script called 'screencheck.sh'

2. Put the following into the file (I often use textwrangler and / or nano).

   #!/bin/bash
   
   count=0
   
   while [ $count -lt $1 ] ; do 
      echo "Count: $count of $1. Pausing for five seconds."
      sleep 5s
      ((count++))
   done
   

3. Open two terminal windows.

4. In one of the terminal windows type screen -ls. You should see a message about no sockets being found.
5. In the second terminal window, change directory to where the script was saved.
6. In the second terminal window type screen -S ScreenCheck screencheck.sh 500. screencheck.sh has to be executable.

7. In the second terminal window, you should see:

   Count: 0 of 500. Pausing for five seconds.
   Count: 1 of 500. Pausing for five seconds.
   Count: 2 of 500. Pausing for five seconds.
   ...
   

8. Disconnect from the screen session by typing ctrl-a d. That's control + a, release both, d key.
9. You should see [detached].
10. In the first terminal, type screen -ls.

11. You should see something like:

    FCH000: ~: screen -ls
    There is a screen on:
       1593.ScreenCheck (Detached)
    1 Socket in /var/folders/pk/l6b5fhkj6mxfpfh8mtgmstg40000gn/T/.screen.
    

12. Reattach to the screen session using screen -R ScreenCheck.

13. You should see something like:

    Count: 226 of 500. Pausing for five seconds.
    Count: 227 of 500. Pausing for five seconds.
    Count: 228 of 500. Pausing for five seconds.
    Count: 229 of 500. Pausing for five seconds.
    ...
    

To see if it is running after logout, log out and ssh to the computer from another computer. screen -ls should show the same screen session as before.

I hope this helps.

Answer 2

Starting a subshell and running the nohup command from there seems to avoid having Terminal kill it off when exiting.

bash -c "nohup sh -c 'while true; do date; sleep 1; done' &"

Not very elegant, but works for me.