Shell Programming and Scripting

I've no idea how people usually do that. I've check at O'Reilly's bash cookbook, and it talks a little about daemonizing the script.

it refers to : 1-Running it in bg with &
2-Redirecting STDIN, STDOUT and STERR
3-Using nohup command to make script not being interrupted by hang up signal on logout

n1 & n2 items are easy stuff that I already know al least a little.

Using nohup, appears to be simple.

But, trouble is that when I try to make it on that way, shell interrupts process if <return> key is pressed

Code:

bash-2.05$ nohup any.sh 0<&- 1>/dev/null 2>&1 &
[1] 16465
bash-2.05$ 
[1]+  Exit 2                  nohup any.sh 0>&- >/dev/null 2>&1
bash-2.05$

So, I wonder now a few things:

1. How can I make that stuff work?
2. Are there many ways to automatize a process?. I wonder what really means to daemonize a script. Will it run as if was in a continous loop?
3. Could that be modified? May I set the script to run to run it every 5 minutes?

I know there are ways to do that, but what I don't know is where to begin looking at

thanks in advice

VIKKKKO

Depends on your needs. A process which needs to run continuously is suitable for "daemonizing"; if it just needs to run periodically, a simple script running at scheduled intervals via crontab would seem like a better approach.

As to why it's exiting, we can't really guess. Can you run it with debugging to see which command it's exiting from? I'd speculate it wants to read input from somewhere, and dies when you turn that off.

Code:

sh -x any.sh 0<&- 1>/dev/null 2>/tmp/any.out &

rather i would phrase it as when the process has to serve adhoc requests and has to be live at any point of time to serve the adhoc requests.

hope you are able to run the script normally, I mean when it is connected to a tty.

Ok. era, i've tried debugging and I've progressed a little.

I've excecuted it on this way:

nohup /~/any.sh 0<&-

so, the output (both STOUT & STERR) were redirected to ./nohup.out


i've checked at nohup.out and i've found my problem:

/usr/bin/command[8]: [argument: not found
/~/any.sh: syntax error at line 14: `DAY=$' unexpected


so, I've realized that I were running it without bash command. So that, I think it was trying to run it on sh, and that fails.



I'm still not understanding what really the deamon does do. I mean: does it run as if it was in continous loop, or have I to make explicity, the loop in the command?.


Perhaps is a good idea too, to force script using bash, but #!/bin/bash does not work for me since bash isn't there. Actually, bash is in diferent routs depending on machine, and i want to do a complete unique code.


thanks both you guys


regards!

I don't think you'll find a very strict definition of what "daemon" means. Matrixmadhan's description is actually a pretty good definition. Anything which runs continuously in the background without any regular user interface is by some definition a "daemon".

If you are writing a program which needs to work like that then yes, you will need to create an infinite loop, or some similar construct.

Many thanks era.

I get that.

regards


VIKKKKO