Or, how about another hack? This would be an ugly polling based solution which you
might dislike.
1. Lets suppose you have a flag - which could be a zero sized file with a
pre-determined name.
2.Then, you
either have a daemontools/bash script with a minimum resolution of 1 second
or a cronjob with a minimum resolution of 1 minute.
3. Your web script removes or creates the file, based on whether you want to start
the service or stop it.
4. When the background process, on one of its polling iteration,
finds that the flag is not present, but service is up, it stops it,
and vice versa.
Pros:
- easy to create.
- Extremely secure. No running of setuid scripts, root web processes etc.
Cons:
- not very elegant, but works.
- poll based. Not probably good for infrequently used services.
The design pattern is similar to what djbdns uses.
- Sandip
On Tue, Jan 22, 2002 at 12:18:24PM +0530, Rajat Bhatia spoke out thus:
> Hi,
> Would it suffice, if in the program we want to run in the background, we do a
>fork, and then terminate the parent process, while the child process starts the
>services as required?
>
> Regards,
> Rajat
>
> Manish K Arya wrote:
>
> > hi
> > thanks for quick reply.
> > actully have made a program that read mysql database in cartain time intervals
>and takes action according to cases.now i want to have a web based panel to start and
>stop that service.
> >
> > On Tue, 22 Jan 2002 11:33:43
> > Kapil Sethi wrote:
> > >I think that is an interesting situation.
> > >
> > >The job of HTTP server is to load a file and transfer the contents to the
> > >client. after the html page is served the server closes the connection. In
> > >case of server parsed documents like cgi / php /asp etc. scripts the server
> > >waits for the appropriate engine to process the request and hand over the
> > >document in HTML format to it. The server then forwards this document to the
> > >client. when you try to execute a program in background using CGI the server
> > >is still waiting for the child program to terminate. In effect waiting for
> > >the complete output which it will forward to client. Thus the server process
> > >waits indefinitely for the child process to terminate. Also as the
> > >background process does not terminate, every request to the cgi script will
> > >create one more instance to the same program in memory overloading your
> > >system.
> > >
> > >So, I think this is a bad idea to create background processes using a web
> > >server.
> > >
> > >Can we know what exactly is the motive, we may be able to suggest some
> > >better way.
> > >
> > >Kapil Sethi
> > >System Administrator
> > >BharatConnect Ltd.
> > >Ph: 011-6430987
> > >----- Original Message -----
> > >From: "Manish K Arya" <[EMAIL PROTECTED]>
> > >To: "general linux" <[EMAIL PROTECTED]>; "linux programmers"
> > ><[EMAIL PROTECTED]>
> > >Sent: Tuesday, January 22, 2002 11:03 AM
> > >Subject: [ilugd]: (No Subject)
> > >
> > >
> > >> hi
> > >> i was trying to run a program in background thru cgi and php.
> > >> i have written a shell script to intialize the C program that i want to
> > >run in background
> > >> like
> > >>
> > >> #/bin/bash
> > >> program&
> > >>
> > >> and now i try to run this shell script thru C cgi using system() in C cgi
> > >and exec() in php.
> > >> program gets started in background properly.but the problem is that web
> > >browser gets busy(loading icon glows).and statements after exec()/system()
> > >are not executed.i dont know why it is happening.
> > >>
> > >> pls suggest
> > >>
> > >> ---
> > >> Manish Kumar Arya
> > >> --------------------------------------------
> > >> While universe
> > >> {
> > >> Object emerges from zero, tends to infinity and finally end in zero.
> > >> }
> > >> --------------------------------------------
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
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> >
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> -- - Popi Classification -------------------------------------------------------
> Classification applies if checked...
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> [ ] Motorola Confidential Proprietary
>
> --- A Nice Quote --------------------------------------------------------------
> "When the only tool you have is a hammer, you tend to treat everything as if it were
>a nail." -- Abraham Maslow
> -- Contact Me -----------------------------------------------------------------
> Rajat Bhatia
> [EMAIL PROTECTED]
> Tel: +91-124-6307212 Ext 1350
> +91-124-6303212 EPABX Operator
> Fax : +91-124-6306679
>
>
--
Sandip Bhattacharya
sandipb @ bigfoot.com
http://www.sandipb.net
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